10 ways to digitize an analog control room by changing the analog meters

Digitizing an analog control room and replacing the analog meters bring many benefits for engineers. 10 methods are highlighted.

By Otek Corp. May 7, 2023

Digital meter insights

  • Many analog control rooms can be upgraded by replacing analog meters for better data transmission and flow.
  • There are many different types of digital meters and some require specific standards — particularly for hazardous applications.

Many industrial automation companies are working on eliminating the stuck needle syndrome, inaccuracy, low resolution, short life expectancy, mechanical wear and tear, ambiguity, parallax and lack of HMI/MMI of all analog meters.

This can be achieved by replacing these millions of meters without changing anything but the meters themselves. No new panels, mounting, wiring, signal, power, control outputs or operators.

No more identical meters with different scale plates or ranges or colors or text or language scale plate behind the filter. No more duplicate spares for emergency replacement and no more six months recalibration or replacement. The results are more accurate data being transmitted to the engineers in the control room and the ability to send this information to the people who need it most.

10 ways to replace digital meters

Consider these methods when replacing analog meters so the process can be simplified and it’s easier to collect and gather data.

  1. Problem: Replace hundreds of different mechanical mountings. This was achieved by developing adapter plates and a hub.
  2. Problem: Replace 100% mechanical existing without changing any of the panels. This was resolved by developing housings with identical mechanical to existing instead of adapter plates and identical circuitry as in the hub and call it stand-alone case.
  3. Problem: Dealing with hundreds of different input signals, power and outputs. The solution: A design field-selectable plugin modules and jumpers was chosen, which was designed as a plug-and-play option that didn’t need soldering.
  4. Problem: Thousands of different scale plates (behind the bezel) with custom scales, text, colors, languages and more. The solution is using an organic white LED bar-digital display and develop a sticky scale plate with any color, text, language field changeable to stick to the front filter of the positive-negative-positive (PNP) meter and add a sticky label on front for easier meter identification.
  5. Emergency spares in inventory might be identical to each other except for their input signal, range, scale and calibration wasting millions of dollars to plant owners. The solution is developing a universal long range 4 to 20 mA current loop transmitter that will accept any of >50 different input signals, 5 different power inputs, 10 controlling outputs and three different 4 to 20 mA current loop outputs including retransmission, externally controlled input signal and proportional-integral-derivative (PID). This was an easy part of the project because all that needed to be done was select the PNP appropriate cases for transmitters, plugin the select power supply, the proper input signal conditioner and plug in the transmitter module. The result was converting a meter into a transmitter within minutes.
  6. They must be field replaceable repairable and calibrated in minutes. Since all meters can be 4 to 20 mA 100% current loop power, all the user has to do is short out the + &- loop terminals, remove old, mount new, connect the two wires of the loop to PNP and remove the jumper.
  7. In one case, a complete nuclear power plant digitization within one outage was resolved by prebuilding the distribution panel to mount all transmitters and wiring. They also prebuilt the DCS/SCADA/DAS and PLC closet and made it compliant to NEI08-09 add the twisted pair of wires for the current loop, use existing wiring and lamps for annunciators.
  8. Problem: Either “smart” (uP based) for computer interface w/serial I/O & NEI08-09 compliant, or “dumb” (no uP) hardware based NEI08-09 exempt. A meter designed for NPP, military and industrial customers was used. It is 100% DCS/SCADA/DAS compatible and Class1E/mil-spec qualified.
  9. For compliance, the digital meters in a particular case had to adhere to military standards 461,462, 167, 901, 810, RTCA 160, NEI08-09, EPRI 102323, IEEE std.323 & 344 compliant to Class1E App. B nuclear.
  10. Digital meters must be field replaceable, modifiable, assembled, calibrated, tested, certifiable and installable by maintenance personnel. This was a time-consuming task because an owner’s manual had to be written with clear instructions of every step and confirmation of every possible combination.

All of the above was possible with plugin modules and jumpers to meet shock & vibration requirements per military specs.

– Edited by Chris Vavra, web content manager, CFE Media and Technology, cvavra@cfemedia.com.