Analog
to Digital
Meter
Upgrades
By Otto Fest, OTEK Corporation and
Brian Shaler, Palisades Nuclear Plant.
Otto Fest
Dr. Fest attended Polytechnic University
where he graduated with a BS in
EE. He taught in
vocational schools
and was assistant
professor until
offered a scholarship
by Heidelberg
University and
Armour Research
Foundation in 1960.
He opted to attend
Illinois Institute
of Technology;
Research Institute
(IITRI) and
graduated with
Ph.D. in EE.
Dr. Fest has worked
for Armour Research
Foundation (ARF) in advance solid state
research and co-authored several patent
papers. He was a contributor to the
development of the PBX at Automatic
Electric Co. and then joined Zenith
Radio Corp. under contract with NASA,
working on the Apollo program. In 1974
he established OTEK Corporation.
Obsolescence of analog meters is
a growing problem for nuclear power
plants. The original manufacturers are
gone now, and the companies that still
provide analog replacement meters are
losing interest in that market. Nuclear
plants need a modern alternative, which
is to say they need a way to incorporate
digital technology. This article discusses
the emergence of three generations of
digital upgrades, and the new technology
meters by OTEK that may finally result
in the industry’s adoption of digital
technology. These new technology
meters make it possible to replace the
old analog meters without the addition
of new control power supplies or wiring
changes.
Most nuclear plant control rooms
were designed and wired for 1950’s (and
earlier) technology, leaving analog me-
ters currently in place in many stations.
Many analog meters are signal powered,
requiring no addi-
tional power supply.
Consequently, panels
did not include ex-
ternal power sources.
Analog meters also
come with their own
set of short-comings
and limitations. An
analog meter is sus-
ceptible to stuck
needles, offers low
accuracy, is sensitive
to shock and vibra-
tion, and the unlit and
inset display with a
spherical lens cre-
ates parallax. These
downfalls are only
amplified by the fact that the units are
not DCS (distributed control system),
SCADA (Supervisory Control and Data
Acquisition), or PAC (Programmable Au-
tomation Controller) compatible.
Today only three manufactures
continue to make analog meters. The
finite amount of competition in the
market allows these companies to charge
thousands of dollars for equipment that
is valued at less than 5% of their cost.
In many cases a plant will pay this large
price tag knowing the meter is not the
best available on the market or of the best
value. In some cases units are purchased
(or scavenged) fromclosed or other plants,
just to keep the reactor operational. No
plant is prepared or willing to shutdown
the reactor at a cost of (approximately) $1
million dollars a day.
Remembering that analog meters
are 1800’s technology and advanced
technology is available, you have to
wonder - why do so many plants insist
on maintaining their I&C rooms with the
same old instruments?
The second generation of instruments
designed to replace analog meters
were digital. These instruments offered
LCD (Liquid Crystal Display) or LED
(Light Emitting Diode) technology. This
opened the door for improved accuracy,
better visibility and extended life and
durability. Digital instruments, although
manufactured by very few companies,
were available through hundreds of
private sellers, distributors, resellers and
system integrators. Anxious to profit
from the new wave of process control
instruments “private label” companies
were everywhere. Of the three displays,
only the LED has survived and is the best.
The concept of the digital
replacement was well received. However,
the cost of the actual implementation
sparked numerous long-term debates.
Digital meters changed the consumer
market by offering numerical display
with illumination interpretation and a
low discrepancy rate, while facilitating
Human to Machine Interface (HMI) for
onsite Automatic Process Control (APC).
Tremendous progress has been made in
the field, except for one important factor.
The meters required an external power
source. By requiring external power, the
second generation of meters came with
its own set of complications.
Since older panels were not designed
to supply enough power for a digital unit,
major redesigns were required for any
plant looking to make the change. To
replace all the meters in a control room,
redesigning, rewiring and installing the
units was in the multi-million dollar
range. This made it uneconomical to
supply a separate power source and invest
in new technology.
While the cost deterred many plants,
some plants adapted a hybrid solution.
32
NuclearPlantJournal.com Nuclear Plant Journal, March-April 2015
