Are Analog Meters Doomed?

The old and faithful analog panel meter, invented by Dr. Edward Weston in 1893, is still in use and dominates our nation’s critical power industries, particularly the nuclear power industry.  Unfortunately, one of the greatest technical and cleanest electrical power options still relies on a 19th century metering technology (D’Arsonval movement).  While analog meters are simple to install and use and have a low manufacturing cost, their positive aspects are offset by their unreliability, inaccuracy and fragility.  Analog meters have a tendency toward stuck needles, inaccurate measurements and erroneous readings by operators.  Even worse, analog panel meters typically only have an accuracy rating of only +/-3-5%.  This rating drops even lower if you include the standard +/-5% precautionary safety factor.  The result is that plants operate below maximum efficiency, losing 8-10% of their optimum electric power output.  This translates into a real loss of about $100,000 per day for a typical reactor that produces about $1,000,000/day of electricity!  Why then, in this age of revolutionary technology, are we still relying on obsolescent analog technology?  The answer is simple, upgrading from analog to digital technology is expensive. 

One hurdle the power industry faces is the need to keep upgrade costs as low as possible.  Ideally, this means avoiding major changes in power source input signals, rewiring and new panel installations.  Another costly hurdle to eliminating inefficient analog meters is the need for security.  Critical information and systems must be kept cyber secure, and this is particularly true of the nuclear industry.  Analog meters are safe because they don’t contain vulnerable digital microprocessors (uP).  Upgrading to digital technology may increase efficiency, but it also subjects the industry to cyber security concerns.  For example, a nuclear power plant I & C (Instrument & Control) room would now have to comply with the Nuclear Regulatory Commission’s cyber-security regulations (NEI 08-09, et. al.).  To get past these hurdles, a power plant could conceivably spend millions of dollars and wait years before the upgrades are completed.  Digital meter technology that could offer a 100% compatible (1:1) analog replacement just didn’t exist, until now.

Otek Corporation has created a new breed of digital meter known as SSAM (which stands for Solid State Analog Meter).  SSAM is hardware only (no microprocessor) multicolor bar-digital meter that is solely powered by a 4-20 mA (~5-60 mW) current loop (typical to most I & C rooms).  In fact, it can be powered by any signal that can provide >5 mW of energy, even if no other power or current is available.  This Powerless TM meter can be used as a basic bar graph (like the analog meter), as a bar-digital (like old digitals), or as a multi-function meter which can be configured in the field by the user.  SSAM will measure, display, control, and transmit AC and/or DC signals without a microprocessor and all with a +/-0.5% digital accuracy.  Since the SSAM has no uP, readout colors are achieved by embedding colored filters into the scale plate which cover the units high-efficiency, pure white LEDs.  Otek Corporation holds many patents in current loop technology and has included many other patented features into their new SSAM units.

This may well be the end of the old analog meter since SSAM can be installed using the existing input signals, wires and panel cut-outs as the old analog meters.  In addition, since SSAM contains no microprocessors, it is not subject to regulatory cyber security compliance conditions.  The total cost to upgrade to SSAM’s more efficient digital technology would be about 1/3 of replacing obsolete analog/digitals, and these units will pay for themselves within a week (assuming a 1% increase in efficiency)!

Our nation’s power industry finally has an affordable digital upgrade solution. All good things must come to an end and the analog meter is near extinction! 

1893 VOLTMETER      LEGACY DB40      OTEK'S SSAM-N 2017