Monday, August 21, 2017

Fieldbus Equipped Process Control Instrumentation: Part Two of Two

(Image courtesy of Lessons in Industrial Instrumentation
and Tony R. Kuphaldt and shared under Creative Commons
4.0 International Public License
Since automatic control decisions in FOUNDATION fieldbus are implemented and executed at the field instrument level, the reliance on digital signals (as opposed to analog) allows for a streamlined configuration of direct control system ports. If the central control device were to become overloaded for any reason, tasks related to control decisions could still be implemented by operators in the field. This decentralization of the system places less burden and emphasis on the overall central control unit, to the point where, theoretically, the central control unit could stop functioning and the instrumentation would continue performing process tasks thanks to the increased autonomy. Allowing for the instrumentation to function at such an increased level of operation provides a proverbial safety net for any system related issues, with the capacity for independent functionality serving as both a precaution and an example for how process technology continues to evolve from analog solutions to fully end to end digital instrumentation.

Even in terms of the FOUNDATION instrumentation itself, there were two levels of networks being developed at this increased level of operation, initially: the first, H1, was considered low speed, while H2 was considered high speed. As the design process unfolded, existing Ethernet technology was discovered to fulfill the needs of the high speed framework, meaning the H2 development was stopped since the existing technology would allow for the H1 network to perform to the desired standards. The physical layer of the H1 constitutes, typically, a two-wire twisted pair ungrounded network cable, a 100 ohm (typical) characteristic impedance, DC power being conveyed over the same two wires as digital data, at least a 31.25 kbps data rate, differential voltage signaling with a defined threshold for both maximum and minimum peak receive rates, and Manchester encoding. Optical fiber can be used on some installations in lieu of the twisted pair cable.

Most of these specifications were exactly designed to withstand extremely challenging process control environments while still not abandoning the philosophy of being easy to build and implement, especially in terms of new system establishment. The most crucial aspects of many process control systems are streamlined together, allowing for consistent communication and synchronization. All aspects are viewable from both the legacy central controller and also via each individual device. Despite the data rate of 31.25 kbps being relatively slow, what is sacrificed in terms of speed is more than made up for in terms of the system being compatible with imperfect cables and other hiccups which may destabilize a network with faster speeds. The evolved technology, ease of installation, and durability have made the H1 network a widely used implementation of the FOUNDATION fieldbus technology. Fieldbus is currently considered one of a few widely adopted industrial process control communications protocols.

Contact Power Specialties with any process instrumentation, or field device communication question you may have. Visit or call (816) 353-6550.

Sunday, August 13, 2017

Fieldbus Equipped Process Control Instrumentation: Part One of Two

(Image courtesy of Lessons in Industrial Instrumentation
and Tony R. Kuphaldt and shared under Creative Commons
4.0 International Public License).
Autonomous control and digital instrumentation are two capabilities enabling highly precise or complex execution of process control functions. FOUNDATION fieldbus instrumentation elevates the level of control afforded to digital field instrumentation where, instead of only communicating with each other, instruments involved in particular process control systems can independently facilitate algorithms typically reserved for instruments solely dedicated to controlling other instruments. Fieldbus capable instrumentation has become the standard instrumentation for many process industry installations due to the fact the FOUNDATION design principle streamlines process systems. A large contributor to FOUNDATION's success has been faster installation as opposed to operational controllers which do not feature the fieldbus configuration. Newer process companies, or process control professionals seeking to establish a new system, have gravitated towards fieldbus due to the combined advantages of system conciseness and ease of implementation.

In a typical digital control system, dedicated controllers communicate with field instrumentation (the HART protocol is a prime example of digital communication at work in the industry). The host system controls configuration of instruments and serves as a central hub where all relevant control decisions are made from a single dedicated controller. Typically, these networks connect controllers and field devices through coupling devices and other "buses" which streamline many different instruments into a complete system.

FOUNDATION fieldbus approaches the same network scheme with an important difference. Whereas in a legacy or more conventional system, either algorithmic or manual decisions would need to be implemented via the dedicated system level controllers, instruments utilizing FOUNDATION fieldbus architecture can execute control algorithms at the local device level. The dedicated controller hub is still present, so that operators can view and monitor the entire network concurrently and make status changes. Algorithmic execution of control functions becomes entirely device reliant thanks to the FOUNDATION protocol. Additionally, even though FOUNDATION implements an advanced configuration, some operators use the capabilities introduced in the fieldbus upgrade to implement specific algorithms via each device while concurrently maintaining algorithms in the central controller. This dual algorithmic configuration allows for several advantages, including the ability for increased system precision.

Since individual devices in the control process are calibrated and able to execute their own control functions, issues in the process with particular devices can be isolated and dealt with in a more specified manner by technicians using the instruments in the field. The central operator retains the capacity to use the control hub to alter and direct the control system.

Stay tuned for Part Two.

Contact Power Specialties with any process instrumentation, or field device communication question you may have. Visit or call (816) 353-6550.

Monday, July 31, 2017

Introducing the Fox FT4A Thermal Mass Flow Meter

The Fox Model FT4A is the newest thermal gas mass flow meter offered from Fox Thermal Instruments.

The Model FT4A measures gas flow rate in standard units (SCFM, NM³/hr, LBS/HR, KG/HR & many more) without the need for temperature and pressure compensation.

A free software tool – FT4A View™ - is available for the Model FT4A that allows the user to connect to and configure the FT4A using a PC or laptop.


Direct Mass Measurement

The Fox Model FT4A measures the mass flow of gases directly in Standard Cubic Feet per Minute (SCFM), Normal Cubic Meters per Hour (NM³/hr), Kilograms per Hour (Kg/Hr), and other mass units without the need for pressure or temperature compensation. One isolated 4 to 20mA output programmable for flow or temperature is standard; HART communication optional. A second output is selectable for pulse or RS485 Modbus RTU.

Outstanding Low Flow Capability, Wide Turn-Down Ratio

The Fox flowmeter is capable of providing precise measurement of extremely low velocity gas flows. This results in a wide measurement range and a turn down ratio up to 1000:1; 100:1 typical.


The non-cantilevered design of the DDC-SensorTM is standard on all Model FT4A flowmeters. Instead of using traditional analog circuitry, the DDC-SensorTM is interfaced directly to the FT4A microprocessor for more speed and programmability.


The Model FT4A has many common gas calibrations pre-programmed into the meter so that the user can select a gas from a list to fit the application. Three gas menus are available: Pure Gas Menu, Mixed Gas Menu, and Oil & Gas Menu.

Probe and Retractor Sizes

The insertion flow meters have a 3/4" robust probe, are easy to install, and can be installed in pipe diameters of 1 1⁄2" to 70". Probe (I) and Retractor (R) sizes are: 6" (06I), 9" (09I), 12" (12I), 15" (15I/15R), 18" (18I/18R), 24" (24I/24R), 30" (30I/30R), and 36" (36I/36R).


The Display and Configuration Panel displays flow rate, flow total, elapsed time (hours since the totalizer was reset), process temperature and alarms. Field configurable variables include flow and temperature engineering units, 4 to 20mA scaling for flow and temperature, standard temperature and pressure (STP), pulse output scaling, zero flow cut off, alarm settings (high flow, low flow, high temp, and low temp), filter setting, and many others.

Digital Communications / FT4A ViewTM

Bus options are RS485 Modbus RTU and HART. The FT4A uses a standard USB port to connect to a PC. Fox's free FT4A ViewTM software provides complete configuration and remote process monitoring functions.

NIST Traceable Calibration

The Fox Calibration laboratory uses NIST traceable flow standards to ensure the highest level of accuracy. A calibration certificate is supplied with every meter.

Discrete Output

The discrete output can be set to provide a signal when alarms are generated.

Enclosure and Area Rating

NEMA 4X enclosure approved for FM and FMc Class I, Division 1; ATEX/IECEx Zone 1 approved. CE mark.

Input Power

Input Power: 12 to 28VDC, 20 watts max. Full Input Power Range: 10 to 30VDC, 20 watts max.

For more information on the FT4A contact Power Specialties at (816) 353-6550 or visit this link for the Power Specialties website.

Monday, July 24, 2017

Power Specialties: Industrial Markets

Established in 1967, Power Specialties was founded on the concept that customer service is of primary importance. Our staff of Sales Engineers are well trained in the application and selection of instrumentation and control products. Specializing in providing instrumentation and control solutions for industry:
  • Ethanol / BioFuel
  • Agricultural and Specialty Chemical
  • Power
  • Pharmaceutical
  • Manufacturing
  • Water/Wastewater
  • Food/Beverage
  • Oil and Gas Production
For more information, visit Power Specialties at or call  (816) 353-6550 .

Tuesday, July 18, 2017

Rotary and Linear Damper Drives for Control of Combustion Air and Flue Gas

Electric Damper Drive
Electric Damper Drive (Rotork)
Combustion air and flue gas damper drives fill a critical role requiring safety, accuracy and reliability above all else. It is critical to deploy the best drive technology to maximize combustion efficiency, minimize emissions and reduce installation costs.

Damper Operator (Drives) Types :

Damper drives can be one of three types: pneumatic, electric, or electro-hydraulic, as described below.
  • Pneumatic. These damper operators are used whenever controls rely primarily on compressed air (pneumatic) for moving operators.
  • Electric. These damper operators are used whenever controls rely primarily electricity as the power source.
  • Electro-hydraulic. These damper operators are the same as the electric type described above, but also have a hydraulic system to position the damper.
Pneumatic Damper Drive
Pneumatic Damper Drive
(Rotork Type K)
A very important part of damper design is determination of damper torque and sizing and selection of damper actuator for the maximum torque. Actuator torque should be selected to provide the maximum torque required to operate the damper as well as to provide margin and allow for degradation over the life of the damper. Actuators should be evaluated for damper blade movement in both directions, at the beginning of blade movement, and while stroking blades through the full cycle of movement.

The Goal for Selecting the Best Drive Technology:

Reduced emissions, lower fuel consumption and improved boiler draft control.

Ways to achieve this goal:
Installed Damper Drive
Installed Damper Drive
  • High speed continuous modulation of ID/FD fan and inlet guide vanes 
  • Improved modulation and control of secondary air dampers 
  • Improved automation and burner management 
  • Quick response to plant demand 
  • Improved reliability in high temperature environments 
  • Precise damper and burner positioning 
  • Simple commissioning and diagnostics 
  • Low running costs, virtually maintenance free 
  • Pneumatic, analog and bus network communications 
For more information, review the document below, or download it at this link on Power Specialties website.

Tuesday, July 11, 2017

Basics of Pressure Measurement: Hydrostatic Pressure

pressure transmitter
Pressure transmitter
Pressure measurement is an inferential way to determine the height of a column of liquid in a vessel in process control. The vertical height of the fluid is directly proportional to the pressure at the bottom of the column, meaning the amount of pressure at the bottom of the column, due to gravity, relies on a constant to indicate a measurement. Regardless of whether the vessel is shaped like a funnel, a tube, a rectangle, or a concave polygon, the relationship between the height of the column and the accumulated fluid pressure is constant. Weight density depends on the liquid being measured, but the same method is used to determine the pressure.

A common method for measuring hydrostatic pressure is a simple gauge. The gauge is installed at the bottom of a vessel containing a column of liquid and returns a measurement in force per unit area units, such as PSI. Gauges can also be calibrated to return measurement in units representing the height of liquid since the linear relationship between the liquid height and the pressure. The particular density of a liquid allows for a calculation of specific gravity, which expresses how dense the liquid is when compared to water. Calculating the level or depth of a column of milk in a food and beverage industry storage vessel requires the hydrostatic pressure and the density of the milk. With these values, along with some constants, the depth of the liquid can be calculated.

The liquid depth measurement can be combined with known dimensions of the holding vessel to calculate the volume of liquid in the container. One measurement is made and combined with a host of constants to determine liquid volume. The density of the liquid must be constant in order for this method to be effective. Density variation would render the hydrostatic pressure measurement unreliable, so the method is best applied to operations where the liquid density is known and constant.

Interestingly, changes in liquid density will have no effect on measurement of liquid mass as opposed to volume as long as the area of the vessel being used to store the liquid remains constant. If a liquid inside a vessel that’s partially full were to experience a temperature increase, resulting in an expansion of volume with correspondingly lower density, the transmitter will be able to still calculate the exact mass of the liquid since the increase in the physical amount of liquid is proportional to a decrease in the liquid’s density. The intersecting relationships between the process variables in hydrostatic pressure measurement demonstrate both the flexibility of process instrumentation and how consistently reliable measurements depend on a number of process related factors.

Contact Power Specialties at (816) 353-6550 or visit with any industrial pressure measurement application of requirement.

Friday, June 30, 2017

Happy Fourth of July from Power Specialties

"We hold these truths to be self-evident, that all men are created equal, that they are endowed by their Creator with certain unalienable Rights, that among these are Life, Liberty and the pursuit of Happiness. — That to secure these rights, Governments are instituted among Men, deriving their just powers from the consent of the governed, — That whenever any Form of Government becomes destructive of these ends, it is the Right of the People to alter or to abolish it, and to institute new Government, laying its foundation on such principles and organizing its powers in such form, as to them shall seem most likely to effect their Safety and Happiness."

THOMAS JEFFERSON, Declaration of Independence

Thursday, June 29, 2017

Proper Wiring of Yokogawa ROTAMASS with Remote Converter

with remote converter.
The ROTAMASS 3 Series mass flowmeter features a heavy wall, seamless, dual tube design uniquely decoupled from any process vibration or pipeline stress guaranteeing reliability and output stability.

The ROTAMASS is available in two designs - an integral converter and a remote converter.

When working with the remote design, it's important to wire the remote converter to the flow tube properly to avoid signal error and faulty readings. The video below carefully explains the proper way to wire the two components together.

For any Yokogawa instrumentation requirement in Kansas, Nebraska, Iowa, or Missouri, contact Power Specialties. Visit or call (816) 353-6550.

Monday, June 19, 2017

Rotary Drives for Industrial Damper and Louver Applications

Type K damper drives
Type K damper drives.
The Type K Range offers rotary and linear pneumatic damper drives for utility power plants, refineries, powerhouse boilers, furnaces and process heaters that require precise combustion air and flue gas handling solutions. Type K damper drives have proven to increase boiler efficiency, reduce maintenance, lower fuel consumption and reduce harmful emissions.
  • Drop-In-Place retrofit requires no field engineering or fabrication 
  • Improved reliability in high temperature environments 
  • Rated for 100% duty-cycle, continuous modulating service 
  • Highly accurate to 0.25% resolution 
  • Discrete contacts (O/C) and pneumatic, analogue or bus network (MOD) communications

Tuesday, June 13, 2017

Product Update: SMARTDAC+ GX/GP Series Recorders & GM Series Data Acquisition System Release 4

Yokogawa Electric Corporation announced it's Release 4 of the SMARTDAC+® GX series panel-mount type paperless recorder, GP series portable paperless recorder, and GM series data acquisition system.

With this latest release, new modules are provided to expand the range of applications possible with SMARTDAC+ systems and improve user convenience. New functions include sampling intervals as short as 1 millisecond and the control and monitoring of up to 20 loops.


Recorders and data acquisition systems (data loggers) are used on production lines and at product development facilities in a variety of industries to acquire, display, and record data on temperature, voltage, current, flow rate, pressure, and other variables. Yokogawa offers a wide range of such products, and is one of the world’s top manufacturers of recorders. Since releasing the SMARTDAC+ data acquisition and control system in 2012, Yokogawa has continued to strengthen it by coming out with a variety of recorders and data acquisition devices that meet market needs and comply with industry-specific requirements and standards.

With this release, Yokogawa provides new modules with strengthened functions that meet customer needs for the acquisition and analysis of detailed data from evaluation tests. These modules decrease the cost of introducing a control application by eliminating the need for the purchase of additional equipment.


The functional enhancements available with Release 4 are as follows:

High-speed analog input module for high-speed sampling.
To improve the safety of electric devices such as the rechargeable batteries used in everything from automobiles to mobile devices, evaluation tests must be conducted to acquire and analyze detailed performance data. For this purpose, sampling at intervals as short as 1 millisecond is desirable. However, this normally requires an expensive, high-performance measuring instrument. When the new high-speed analog input module, a SMARTDAC+ system can sample data at intervals as brief as 1 millisecond, which is 1/100th that of any preceding Yokogawa product. This is suitable for such high performance applications such as measurement of the transient current in rechargeable batteries to vibration in power plant turbines. A dual interval function has also been added that enables the SMARTDAC+ to efficiently and simultaneously collect data on slowly changing signals (e.g., temperature) and quickly changing signals (e.g., pressure and vibration).

PID control module for control function
In applications that need both control and recording, such as controlling the temperature of an industrial furnace or the dosage process at a water treatment plant, there is a need for systems that do not require engineering and can be quickly and easily commissioned. In a typical control and monitoring application, a separate recorder and controller is required to control temperature, flow rate and pressure. At the same time, a data acquisition station must communicate with the controller to ensure data is being capture and recorded. It is time consuming and oftentimes confusing, to ensure the controller and the data acquisition station is communicating seamlessly. By combining continuous recording function of the SMARTDAC+ and PID control module into a single platform, customers can now seamlessly control and record critical process data in one system. The SMARTDAC+ can control, monitor and record up to 20 loops. Each PID control module comes with 2 analog inputs, 2 analog outputs, 8 digital inputs and 8 digital outputs.

Four-wire RTD/resistance module for precise temperature measurement
While three-wire RTDs are widely used in many fields such as research institutes to manufacturing, some applications require higher level of precision and accuracy that is only possible with 4-wire RTDs. A 4-wire RTD is the sensor of choice for laboratory applications where accuracy, precision, and repeatability are extremely important. To satisfy this need, Yokogawa has released a 4-wire RTD/resistance module for the SMARTDAC+

Target Markets

GX series: Production of iron and steel, petrochemicals, chemicals, pulp and paper, foods, pharmaceuticals, and electrical equipment/electronics; water supply and wastewater treatment facilities.

GP series: Development of home appliances, automobiles, semiconductors, and energy-related technologies; universities; research institutes.

GM series: Both of the above target markets.

For more information on the SMARTDAC+ GX/GP Series Recorders & GM Series Data Acquisition System in Kansas, Missouri, Iowa, or Nebraska contact Power Specialties at (816) 353-6550 or by visiting

Wednesday, May 31, 2017

Process Weighing Controller: The BLH G5 Tech Manual

G5 Instruments
BLH Nobel G5 Instrument (panel mount)

The G5 Instruments are high performance single-channel weight indicators (PM model, panel mounted) or weight transmitters (RM model, DIN rail mounted) intended for industrial systems.

The basic function is to convert the signals from strain gauge transducers to useful weight information. Transducer excitation is included as well as parameter controlled signal processing, indication of output levels, error supervision and operation of optional external equipment.

As long as the error supervision detects no error, a signal called ‘In process’ is then present but if an error is detected, ‘In process’ will be off and a specific error message will be displayed. ‘In process’ can be set to control any digital output. Note that there are weighing channel specific and instrument specific error detection.

All functions in the G5 Instrument are controlled by set-up parameters. Setting of parameter values can be done from the PM front panel. Set-up of a RM model must be done with a web browser in a PC that is connected to the instrument via Ethernet. Maintenance functions can be accessed locally (PM) or remotely (PM and RM).

View the complete Technical Manual below, or download the G5 Tech Manual from here.

Saturday, May 27, 2017

A Precise Combustion Airflow Measurement Station Designed for the Power Industry

The objectives in the power industry today are twofold;
  • To lower emissions 
  • Increase plant performance
Precise measurement of combustion airflow and fuel rates positively contributes to achieving those objectives, by providing the information needed to optimize stoichiometric ratios and facilitate more complete, stable combustion. Usable measurements cannot be obtained from existing devices such as Venturis, foils, jamb tubes, etc., or instrumentation such as thermal anemometers due to limited available straight duct runs, low flow rates, proximity to modulating control dampers, broad turndown range, and high concentrations of airborne particulate (flyash). 

There is a product, however, by Air Monitor Corporation that reliably and consistently provides precise combustion airflow measurement. The CA Station has both an integral airflow processing cell and Fechheimer-Pitot measurement technology and is engineered to meet the challenging operating conditions of the typical power plant. It's capable of providing mass flow measurement of PA, SA, and OFA within an accuracy of ±2-3% of actual airflow.
CA Station
The Air Monitor CA Station

While the main functions of primary air are to first dry and then pneumatically convey the pulverized coal from the mill to the individual burners, it also determines coal particle velocity at the burner exit, influencing the flame position relative to the burner tip and impacting flame stability, both key factors in achieving optimized burner performance. Accurate PA measurement obtained with a CA Station can contribute to reducing NOx and CO, improving flame stability, avoidance of coal pipe layout, minimizing LOI/UBC, reducing waterwall corrosion, and increasing combustion efficiency.

The CA Station is also ideally suited to measure SA entering each burner level of a partitioned windbox, SA being taken out of a windbox to supply multiple OFA ports, at the ducted inlet of FD fans, and bulk SA entering each windbox of a corner fired unit.

For more information about the CA Staton, contact Power Specialties by visiting or calling (816) 353-6550.

Tuesday, May 16, 2017

DAQ - Data Acquisition's Role in Process Control

Data acquisition
DAQ incorporating data acquisition, process
control, recording, display and networking
in a single compact unit
Courtesy Yokogawa Corp.
Data acquisition, like an equipment acquisition, is the procurement of an asset. Data is an asset. It helps an operator evaluate process or business conditions and make decisions that impact the success of the organization.

Let’s define data acquisition as the sampling of signals that represent a measurement of physical conditions and the conversion of those signals into a numeric form that can be processed by a computer. A data acquisition system will generally consist of sensors, transmitters, converters, processors, and other devices which perform specialized functions in gathering measurements and transforming them into a usable form.

Industrial process operators and stakeholders benefit from the collection and analysis of data by enhancing performance of valuable facets of the process or activity. Data acquisition, commonly known as DAQ, is widely employed in high stakes and sophisticated processes where there is a true need to know current conditions. A desire for increased profit drives the need for increased process output and efficiency. A desire to reduce risk of loss drives the need for reduced downtime and improved safety. Today, there are likely many useful applications for data acquisition that are not being tapped to their fullest potential. The modest cost and simplicity of putting a data acquisition system in place, compared to the benefits that can be derived from a useful analysis of the data for your operation or process, makes the installation of a data acquisition system a positive move for even small and unsophisticated operators in today’s market.

What we call DAQ today started in the 1960’s when computers became available to businesses of large scale and deep pockets. By the 1980’s, personal computers employed in the business environment could be outfitted with input cards that enabled the PC to read sensor data. Today, there is an immense array of measurement and data collection devices available, spanning the extremes of price points and technical capability. For a reasonable cost, you can measure and collect performance data on just about anything.

Data acquisition has an application anywhere an operator or stakeholder can benefit from knowing what is occurring within the bounds of their process or operation. Here is a partial list of the many physical conditions that can be measured in industrial settings:
  • Temperature
  • Pressure
  • Flow
  • Force
  • Switch Open or Closed
  • Rotational or Linear Position
  • Light Intensity
  • Voltage
  • Current
  • Images
  • Rotational Speed
Consider your industrial process or operation. Are there things you would like to know about it that you do not? Would you like to increase your insight into the workings of the process, how changes in one condition may impact another? Do you know what operating condition of each component of your process will produce the best outcomes? Is reducing maintenance, or heading off a failure condition before it occurs something you would like to have in your operation? Applying your creativity, ingenuity and technical knowledge, along with the help of a product expert, will help you get the information you need to improve the outcomes from your industrial process or operation. 

Monday, May 8, 2017

Wireless Instrumentation In Process Measurement and Control

Wireless Transmitters
Wireless Instrumentation (Yokogawa)
In process control, various devices produce signals which represent flow, temperature, pressure, and other measurable elements of the process. In delivering the process value from the measurement point to the point of decision, also known as the controller, systems have traditionally relied on wires. More recently, industrial wireless networks have evolved, though point-to-point wireless systems are still available and in use. A common operating protocol today is known as WirelessHARTTM, which features the same hallmarks of control and diagnostics featured in wired systems without any accompanying cables.

Wireless devices and wired devices can co-exist on the same network. The installation costs of wireless networks are decidedly lower than wired networks due to the reduction in labor and materials for the wireless arrangement. Wireless networks are also more efficient than their wired peers in regards to auxiliary measurements, involving measurement of substances at several points. Adding robustness to wireless, self-organizing networks is easy, because when new wireless components are introduced to a network, they can link to the existing network without needing to be reconfigured manually. Gateways can accommodate a large number of devices, allowing a very elastic range for expansion.

In a coal fired plant, plant operators walk a tightrope in monitoring multiple elements of the process. They calibrate limestone feed rates in conjunction with desulfurization systems, using target values determined experientially. A difficult process environment results from elevated slurry temperature, and the associated pH sensors can only last for a limited time under such conditions. Thanks to the expandability of wireless transmitters, the incremental cost is reduced thanks to the flexibility of installing new measurement loops. In regards to maintenance, the status of wireless devices is consistently transmitted alongside the process variable. Fewer manual checks are needed, and preventative measures may be reduced compared to wired networks.

Time Synchronized Mesh Protocol (TSMP) ensures correct timing for individual transmissions, which lets every transmitter's radio and processor "rest" between either sending or receiving a transmission. To compensate for the lack of a physical wire, in terms of security, wireless networks are equipped with a combination of authentication, encryption, verification, and key management. The amalgamation of these security practices delivers wireless network security equal to that of a wired system. The multilayered approach, anchored by gateway key-management, presents a defense sequence. Thanks to the advancements in modern field networking technology, interference due to noise from other networks has been minimized to the point of being a rare concern. Even with the rarity, fail-safes are included in WirelessHARTTM.

All security functions are handled by the network autonomously, meaning manual configuration is unnecessary. In addition to process control environments, power plants will typically use two simultaneous wireless networks. Transmitters allow both safety showers and eyewash stations to trigger an alarm at the point of control when activated. Thanks to reduced cost, and their ease of applicability in environments challenging to wired systems, along with their developed performance and security, wireless industrial connectivity will continue to expand.

For more information on wireless instrumentation, review the document below. Please feel free to call Power Specialties at (816) 353-6550 to speak with an applications specialist.

Sunday, April 30, 2017

PID Control Tutorial

 YS1700 Programmable Indicating Controller
PID is an acronym for proportional band, integral and derivative. This control action allows a measurement (process variable) to be controlled at a desired set point by continuously adjusting a control output. These control parameters act on the error or deviation between set point and process variable.

P: Proportional Band in %
I: Integral Time in sec/repeat
D: Derivative Time in seconds

Proportional Control

PID Control TutorialWith proportional band, the controller output changes in "proportion" to the error between process variable and set point. The amplitude of the change is adjustable from 1% to 999.9%.

Proportional Control

Refer to Figure 1. This example of a temperature controller shows a proportional band setting of 5%.

  • Set point = 500°
  • Measurement range = 0-1000°
  • 5% PB = 5% of 1000° = 50°
  • 100% output at 475° (2.5% of 1000°)
  • 0% output at 525° (2.5% of 1000°)

If the process variable equals the set point (500°), there is a 50% output. As the temperature decreases, the proportional band increases the output linearly toward 100% as the temperature falls toward 475°. The output decreases below 50% as the temperature rises toward 525°.

In this example, a small change in temperature provides a large change in output. If the setting is too small for the process dynamics, oscillations will occur and will not settle at set point. A large PB setting makes the controller act sluggish and will not respond adequately to upsets. Since proportional control does not incorporate the time that the error has existed, there will always be an offset from set point.

Typically, flow or pressure controllers have a much larger proportional setting due to a possible narrower measurement range and fast process reaction to a change in the control output. For example, a flow controller may have an input range of 0 to 60gpm and a set point of 30gpm.

  • Measurement range = 60gpm
  • Set point = 30gpm
  • 100% PB = 100% of 60 = 60gpm
  • 100% output at 0gpm
  • 0% output at 60gpm

Proportional + Manual Reset

PID Control TutorialTo eliminate the inherent offset observed with proportional control, a manual reset function can be used. Virtually no process requires precisely 50% output to maintain the process variable at the set point. An offset will be present. Manual reset allows the user to bias the output accordingly to compensate for the steady state offset using P only. Refer to Figure 2.

Proportional + Automatic Reset (Integral)

PID Control TutorialAutomatic reset or integral action corrects for any offset between set point and process variable
automatically by shifting the proportional band over a pre-defined time. The integral time repeats the proportional action over the time set. Integral redefines the output requirements at the set point until the process variable and set point are equal. Integral engineering units vary by controller manufacturer. Some use repeats/minute (reset rate), minutes/repeat or seconds/repeat. In Figure 3, seconds/repeat is used. The integral term is added as follows:

Proportional + Automatic Reset (Integral)
The smaller the integral number, the proportional action will be repeated more often. If integral is too small, the process variable will oscillate through set point and create erratic control action. If the number is too large, the action will be sluggish and unable to compensate for process upsets.

The integral number should be approximately 5 times the dead/lag time of the process variable. If the output is manually changed, dead time is defined as the time required for the process variable to initially react after the change. The length of time that it takes for the process variable to stabilize at a steady state is lag time.

  • Example: 40 sec (dead/lag) x 5 = 200 sec/repeat

Proportional + Integral + Derivative

PID Control TutorialDerivative action is used primarily in processes with long dead and lag times. This control function looks at the rate of change of the error and adjusts the control output based on that rate. The derivative term is added to the control algorithm as follows:
Proportional + Integral + Derivative

The amount of derivative added to the control output is based in time units. Figure 4 shows how derivative acts on the proportional band. The dashed line shows a proportional only control due to a process variable error from set point.

Using derivative (solid line), the control output jumps up, rises in a ramp and then falls back to proportional control action when the error becomes constant. In essence, it applies the "brakes" on the process error by quickly shifting the proportional band. Derivative has no effect on the output if the error is not changing. The derivative term should be approximately ¼ the integral time.

Derivative is typically not used in control loops with short dead/lag time, e. g., flow or pressure. This is an anticipatory action that will contribute to the inherent instability of these fast acting control loops.

Reprinted with permission from Yokogawa Corp.

Thursday, April 27, 2017

Manual Tank Level Transmitter Adjustment on Yokogawa DPharp Transmitters

Yokogawa DPharp
If you have ever replaced a level transmitter with remote seals on a tank, you know the problems you may face if the tank can't be empty to allow you to correct for an elevated or suppress zero. With today's smart transmitters, this is now an easy thing to do.

Watch the video below for a quick tutorial on spanning and zero'ing the level transmitter.

For more information about Yokogawa products in Kansas, Missouri, Iowa, and Nebraska, contact Power Specialties by visiting or calling (816) 353-6550.

Saturday, April 22, 2017

Measuring Exact Resultant Forces In Web Tension

Accuracy and consistency of web tension
Accuracy and consistency of web tension is critical.
Paper quality is determined by several factors including density and wrinkling. Problems in these areas are common in the paper industry. Uneven density and wrinkling of paper reels occurs if there is inadequate control over the positions and forces that control critical stages of the winding process, i.e. winding and spool transfer from the primary arm to the secondary arm. Because paper is sold by the ton not by the foot, the density is obviously extremely important. Wrinkling causes big problems in newspaper manufacture as paper breaks lead to stoppage of the printing presses.

One typical problem occurs when the nip force is controlled by measuring the pressures in the cylinders. Because the cylinders are mounted some distance away from the spool, where the nip force is actually generated, the friction that arises in the machine reduces the accuracy of the measurement results. As the mechanical components in cylinders become worn, this problem grows and the inaccuracy of measurements increases. If you do not have force control on both sides, and do not have control over the prevailing conditions for each reel, the nip forces will lack repeatability. This increases the risk of varying density and wrinkle formation, both when changing reels, and during winding where paper breaks may also occur. When lowering the spool from the primary arm to the secondary arm, changes may occur in the lowering speed, and misalignment between the reels may also result in varying density, wrinkles, and paper breaks.
Accuracy and consistency of web tension
One solution from BLH Nobel is based on mounting load cells directly at the point of force application, as well as on the position sensors in each cylinder. The load cells are therefore installed in the primary arm and secondary arm, and in the spool clamp. This allows us to measure values in real time, which means that we know the actual forces in the critical transfer from the primary to the secondary arm. Acceleration speed and force can then be adjusted by positioning cylinders that are controlled by means of software.

By adopting load cells, paper reels of the right density, with wrinkle free paper, and less paper breaks are the outcome. In a typical mill with 3 to 4 percent of the jumbo role being rejected due to wrinkling, using load cells reduced the waste to less than 0.5 percent.
For more information, visit Power Specialties at or call (816) 353-6550.

Friday, April 14, 2017

Introduction to Industrial Transmitters: Transmitters 101

Differential Pressure Transmitter
Differential Pressure Transmitter
Transmitters are process control field devices. They receive input from a connected process sensor, then convert the sensor signal to an output signal using a transmission protocol. The output signal is passed to a monitoring, control, or decision device for use in documenting, regulating, or monitoring a process or operation.

In general, transmitters accomplish three steps, including converting the initial signal twice.

The first step is the initial conversion which alters the input signal to make it linear. After an amplification of the converted signal, the second conversion changes the signal into either a standard electrical or pneumatic output signal that can be utilized by receiving instruments and devices. The third and final step is the actual output of the electrical or pneumatic signal to utilization equipment  controllers, PLC, recorder, etc.

Transmitters are available for almost every measured parameter in process control, and often referred to according to the process condition which they measure. Some examples.
  • Pressure transmitters
  • Temperature transmitters
  • Flow transmitters
  • Level transmitters
  • Vibration transmitters
  • Current, voltage & power transmitters
  • Level Transmitter
    Level Transmitter (MTS)
  • PH, conductivity, dissolved gas transmitters, etc. 
Output signals for transmitters, when electrical, often are either voltage (1-5 or 2-10 volts DC) or
current (4-20 mA). Power requirements can vary among products, but are often 110/220 VAC or 24 VDC.  Low power consumption by electrical transmitters can permit some units to be loop powered, operating from the voltage applied to the output current loop. These devices are also called two-wire transmitters because only two conductors are connected to the unit. Unlike the two wire system which only needs two wires to power the transmitter and analog signal output, the four-wire system requires four separate conductors, with one pair serving as the power supply to the unit and a separate pair providing the output signal path. Pneumatic transmitters, while still in use, are continuously being supplanted by electrical units that provide adequate levels of safety and functionality in environments previously only served by pneumatic units.

Temperature and Flow Transmitter
Temperature and Flow Transmitter
(Fox Thermal Instrument)
Many transmitters are provided with higher order functions in addition to merely converting an input signal to an output signal. On board displays, keypads, Bluetooth connectivity, and a host of industry standard communication protocols can also be had as an integral part of many process transmitters. Other functions that provide alarm or safety action are more frequently part of the transmitter package, as well.

Wireless transmitters are also available, with some operating from battery power and negating the need for any wired connection at all. Process transmitters have evolved from simple signal conversion devices to higher functioning, efficient, easy to apply and maintain instruments utilized for providing input to process control systems.

Friday, March 31, 2017

The Vibrating Fork Industrial Liquid Level Switch: Operation and Application

vibrating fork level switch
Vibrating Fork Level
Switch (Hawk)

When asked the primary reason to remember the year 1711, the event probably not on the minds of many is the invention of a device called the tuning fork. The tuning fork has been used as an source of resonating pitch for over three hundred years, and is still used to tune musical instruments today. While the tuning fork was initially applied to tune musical instruments, the concept of resonant frequency of a material or object has been utilized in numerous commercial, scientific, and industrial applications to provide feedback or insight into a process or operation. The vibrating fork level switch is one such industrial application where resonant frequency is used to deliver a data point or provide a control output for process operation.

The operating principle of the vibrating fork is based on the oscillating fork resonating at a known frequency in air when it is set in motion. Upon contacting a medium other than air, the resonant frequency is shifted, depending on the medium contacting or immersing the fork. Typically, fork-type level switches are installed on either the side or the top of a liquid process tank. An exciter keeps the fork oscillating, and a detector circuit monitors fork vibrating frequency, providing a change in the output signal when the frequency changes. Contact or immersion of the fork in liquid will change the fork vibrating frequency sufficiently to produce a change in output signal. Depending on the configuration of the level switch, it can function as a liquid level alarm, or provide a control output for a pump, valve, or other device. Sensor response, the change in fork vibration frequency, is a function of liquid density. Liquids with greater density will generally produce a larger frequency shift in the vibrating fork.

vibrating fork level switchThe wide use of vibrating level switches across various process industries is a testament to the reliability of the technology. The devices protect against overfill, indicate high and low points inside tanks, and are useful over a wide range of temperatures. A sturdy design, coupled with product variants that include a variety of sensor materials, selectable probe length, and specialized output features make vibrating fork switches applicable in many operations where level indication is needed. Chemical processing, mining, food and beverage, plastics, and other industries utilize the switches, thanks to their customizable designs and consistent performance. An advantage offered by vibrating fork level switches is a resistance to factors that sometimes confound other technologies employed for level indication. The devices will reliably function despite flow, bubbles, foam, vibration, and coating complexities related to the subject liquids. Additionally, vibrating fork switches are reliable in both high level and low level indication scenarios.

Highly viscous liquids are generally not good candidates for the application of a vibrating fork level switch. Some liquids present the potential for material accumulation between the forks, possibly resulting in poor performance. Both of these limitations are addressed by various design features incorporated by different manufacturers.

For more information, visit Power Specialties web site here or call (816) 353-6550.

Thursday, March 30, 2017

Industrial Steam Boiler Optimization Toolkit

Steam generation
Steam generation
The primary function of a utility boiler is to convert water into steam to be used by a steam turbine/ generator in producing electricity. The boiler consists of a furnace, where air and fuel are combined and burned to produce combustion gases, and a feedwater tube system, the contents of which are heated by these gases. The tubes are connected to the steam drum, where the generated water vapor is drawn. In larger utility boilers, if superheated steam (low vapor saturation) is to be generated, the steam through the drum is passed through superheated tubes, which are also exposed to combustion gases. Boiler drum pressures can reach 2800 psi with temperatures over 680°F. Small to intermediate size boilers can reach drum pressures between 800 and 900 psi at temperatures of only 520°F if
superheated steam is desired. Small to intermediate size boilers are only being considered for this application note.

Bolier optimizationWith oil‐burning and gas‐burning boiler efficiencies over 90%, power plants are examining all associated processes and controls for efficiency improvements. Between 1 and 3% of the gross work produced by a boiler is used to pump feedwater. One method of improving overall efficiency is by controlling feedwater pump speed to save on pump power.

Read the entire optimization toolkit below (courtesy of Yokogawa).

Friday, March 24, 2017

New Power Specialties Company Video

Here is a new, short, introductory video about Power Specialties.

Celebrating our 50th year in business, Power Specialties was founded on the concept that customer service is of primary importance. Our staff of Sales Engineers are well trained in the application and selection of instrumentation and control products. Specializing in providing instrumentation and control solutions for industry:
  • Ethanol / BioFuel 
  • Agricultural and Specialty Chemical 
  • Power 
  • Pharmaceutical 
  • Manufacturing 
  • Oil and Gas Production

Thursday, March 16, 2017

Basics of Load Cells Used in Process Weighing

BLH KIS Load Cell
Load cell with many industrial uses
including the weighing of hoppers,
mixing/blending tanks, and conveyors.
(Courtesy of BLH Nobel)   
In industrial application of process measurement and control, principles of the physical sciences are combined with technology and engineering to create devices essential to modern high speed, high accuracy system operation.

Load cells are the key components applied to weighing materials in modern processing. Load cells are utilized throughout many industries in process weighing operations. In application, a load cell can be adapted for measurement of items from the very small to the very large.

In essence, a load cell is a measurement tool which functions as a transducer, predictably converting force into a unit of measurable electrical output. While many types of load cells are available, the most popular cell in multiple industries is a strain gauge based cell. These strain gauge cells typically function with an accuracy range between 0.03% and 0.25%. Pneumatically based load cells are ideal for situations requiring intrinsic safety and optimal hygiene and, for locations without a power grid, there are even hydraulic load cells, which function without need for a power supply. These different types of load cells follow the same principle of operation: a force acts upon the cell (typically the weight of material or an object) which is then returned as a value. Processing the value yields an indication of weight in engineering units. For strain gauge cells, the principle of deformation applies, where extremely small amounts of deformation, directly related to the stress or strain being applied to the cell, are output as an electrical signal with value proportional to the load applied to the cell. The operating principle allows for development of devices delivering accurate, precise measurements of a wide range of industrial products. Advantages of load cells include their longevity, accuracy, and adaptability to many applications, all of which contribute to their usefulness in so many industries and applications.

For more information on any process weighing application, visit Power Specialties at or call (816) 353-6550.

Tuesday, February 28, 2017

Showing the Difference in Function Between High and Low Pressure Ports on a Differential Pressure Transmitter

The following video demonstrates the different responses of a differential pressure transmitter to both positive and negative pressures applied to its high and low pressure ports. The response of pressure and vacuum to the "high" port is opposite the effect of pressure and vacuum (respectively) applied to the "low" port.

Monday, February 27, 2017

Industrial Temperature Sensors and Indicators

Variety of electrical temperature sensors
Variety of electrical temperature sensors (Pyromation)
Temperature sensors are vital to everyday products and in the manufacturing of just about every product we use. Household ovens, refrigerators, and air conditioners all depend on temperature control to function properly and temperature control is essential in all process industries such as chemical, power, refinery, food processing, telecom, cement, fertilizer, pull & paper, plastics and petro-chemical.

Temperature sensors are devices which are used to temperature measurement of a medium (i.e. liquid, solid or gas). The sensor detects change in the temperature, and accordingly, change its physical or electrical property in a manner that can be measured. These sensors come in many different forms and are used for a wide variety of applications.

We as human’s simply sense temperature as hot or cold, but in process control, precise measurement of temperature is required in order to control a process efficiently. Accordingly, the correct temperature sensing device needs to be properly selected.

Types of Temperature Sensors

vapor actuated temperature indicator
Vapor actuated temperature indicator (REOTEMP)
Mechanical temperature sensors and indicators:

Devices that use the physical expansion and contraction of materials (like non-compressable fluids,
vapors, or differential metals) to mechanically open or close a set of contacts.

  • Examples of mechanical temperature sensors are bulb and capillary thermostats, thermometers, mechanical temperature switches, and bi-metallic thermostats.
Electrical temperature sensors:

These sensors undergo a measurable electrical change such as resistance, voltage, or current proportional to a given change in temperature.
Temperature Probe Assembly
Temperature Probe Assembly

  • Examples are thermocouples which generate a micro-voltage based upon a temperature differential between two dissimilar metals; RTDs that increase resistance as the sensing temperature increases; and thermistors,  which dramatically decrease resistance as temperature increases. 
Electrical temperature sensors can be housed in a wide variety of sheaths and/or wells for protection, and come in varying tolerances and accuracies to best suit their intended use.

For more information on temperature sensors, contact Power Specialties at (816) 353-6550 or visit

Basics of Rotameters (Variable Area Flowmeters)

Rotameter by Yokogawa
Rotameter (Yokogawa)
A rotameter is a flow measuring device that belongs to a group of instruments called variable area flowmeters. For decades variable area flowmeters have become established in industrial measurement technology with an economical, mature measurement principle.

The variable area flowmeter is an instrument for metering the flowrate of liquids and gases in a pipeline. It includes a vertically oriented conical tube, whose diameter is larger at the top than at the bottom, through which the fluid flows upward and in which a vertically moving float is positioned. The height of the float in the tube increases as the flowrate increases in such a manner that the resistance to the flow is always balanced by the weight of the float and remains constant regardless of the flowrate. The height of the float in the tube is a measure of the flowrate.

The value of the flowrate can be read from a scale. Variable area flowmeters are the most cost effective solution for almost all applications involving the measurement of industrial process liquids, gases or steam. They meet the application requirements by featuring a wide range of design varieties and sizes.

Rotameters offer long life and high reproducibility and are excellent mechanical back-up meters because no external power supply is needed. For more information on rotameters (variable area flowmeters) visit or call Power Specialties at (816) 353-6550.

The video below does a great job introducing the various types and uses for rotameters.