Cronin’s Workshop: Monitoring Systems
by Dennis Cronin
October 1, 2009
The need for cleanliness and power back-up
Data center operators spend thousands
of dollars annually to keep dust and dirt out of their data centers
for fear that contamination may cause a short across some inner
circuit. Zinc whiskers (see p. 34) and dust from drywall produce many
of the contaminants that cause shorts on circuit boards.
In
recent years the industry has become passionate about monitoring
anything and everything inside the data center and in its supporting
infrastructure. It’s reached the point that the reliability of the
data collected has become as important as the data processed by the
data center.
This passion for information has
created a whole new distributed system of electronics in electrical
and mechanical gear. We now place PLCs, BMS cabinets, BAS cabinets,
and a multitude of other distributed processors in unprotected
environments throughout our facilities. Further, the demand for
instant and accurate information about the data center operation has
driven our conversion from dumb contact closures and 4-20 mA
proportional signals to intelligent circuits that talk to the system
that monitors the status of the data center along with diagnostics of
the monitoring circuits as well.
Although
monitoring of mechanical systems continues to increase at a good
clip, electrical monitoring seems to be advancing at lightning speed.
At every level of the one-line, the industry is monitoring volts,
amps, kW, kVA, kVAR, circuit breaker positions, heat, power quality,
and more. We measure and monitor at the utility entrance, the
generators, the transformers, the PDUs, the remote power panels, and
the cabinet power strips right down to the outlet.
As
our zeal for this information causes it to be more readily available,
we continue to increase our dependence on it. New applications today
provide real-time analysis of the daily operations and instant
notification in changes of state. Today, almost every system does
change of status notifications via text messaging, e-mail, pagers,
radio, and automatic call notices. Some systems are now sufficiently
sophisticated that they try multiple approaches until the individual
being notified acknowledges the notice, which is then time stamped
and logged.
The story here is that we are
creating distributed data centers that monitor, report, and control
our primary data center, but we don not pay the same attention to the
data centers as our primary data centers.
I
recently came across a data center where the vendor supplying the
EPMS (electric power monitoring system) furnished a mini-UPS for the
head end but nothing for the remote input electronics. The irony is
that this EPMS was doing power quality monitoring while it was
running blind on every power excursion. The power quality excursions
were never recorded.
I thought the vendor’s
logic was inconsistent but being curious about what others thought, I
posed the question to different industry groups. The results were
nearly unanimous. Here are a few of the excerpts from the
replies:
The Question
When EPMS is installed in incoming
service switch gear that has electrically operated CBs (circuit
breakers) and station batteries, the EPMS is powered off the station
batteries and therefore is unaffected by power interruptions.
What is your opinion when the incoming
service switch gear only has manually operated CBs and therefore no
station batteries?
Would you specify the EPMS
with a UPS or other form of power backup to operate continuously
during an interruption of the primary service power?
The Design Engineer
“Absolutely yes. If one is going to
the added expense of specifying the installation of a qualified EPMS
in the service entrance switch gear, and presumably the
standby/emergency power switch gear equipment, then, whether the
breakers are electrically or manually operated, the EPMS must stay
operational under every reasonable ‘failure mode’ one might
envision.”
IT at a Server Manufacturer
“In today’s world, having a
facility that is NOT instrumented in most every way possible is
careless. Data is crucial to forming information, and information is
crucial to making decisions. The cost of instrumentation is
inconsequential to the value of the data you protect, so it should be
hard to justify a denial of action.
“That
being said, keep in mind that IT systems are accelerating their
ability to capture, store, and analyze environmental and electrical
data that has been traditionally managed by other types of systems.
“The fact is that IT systems are embracing
environmental and electrical measurement telemetry features, largely
because we can use the data to make better power management decisions
on the fly, and provide better information to the facility.”
From a Switch Gear Manufacturer
“Great topic. I would always
recommend some sort of continuous power to the metering and
monitoring devices. The benefit is for the advance metering with
power quality detection to show the downward spiral of the electrical
system data and most importantly the startup or return of the
electrical system. When you lose power, advanced monitoring can tell
you the magnitude, duration, and most importantly, the direction the
event is coming from. When power is re-applied, the monitoring
devices are in a “boot” cycle that may take a few seconds to
regain its full monitoring capabilities. This is an eternity in
electrical terms and may lead to missing critical data for this
duration. In the restart mode, the advanced metering data will show
system loading, motor starting curves, chiller time delay
verification, and help understand system restart stability. This
information is priceless and the cost of continuous control power is
minimal compared to the benefit of the data produced. Power outages
sometimes cannot be prevented. At least with continuous control
power, you will have an explanation what happened, when, where, and
how can you improve the restart.”
The Guarded Dissenter, A Contractor:
“At the end of the day it is all bent
metal managed by man. I do not suggest the caveman approach to
measuring and monitoring, but I have had it with the special sauce of
the day to achieve a PUE or other new math metric to keep an
unsuspecting client or boss happy. Drive slowly here. We have all
ripped out someone else’s best practice or ‘have to have’
solution. Clients are no longer going to get vendored into new
software, hardware, and retrofit cost with unclear long-term benefits
or TCO enhancements. Today, you can measure or monitor yourself into
a coma...careful....”
Consensus?
So everyone (except the operator of the
site that got me started on this research) agrees. Because of the
criticality of the data, these distributed electronics need power
back-up. So then, what about the environmental needs of these
electronics? We’ve established that they are critical, so why do we
subject them to different environmental standards?
The
most obvious difference in treatment has to do with cleanliness. When
new data centers are built most users will not install their
computers until the data center environment is at near clean-room
condition. Yet the electrical and mechanical spaces housing the
infrastructure that supports our critical data centers are often
loaded with dust, dirt, and debris. When these areas are cleaned, it
is usually done with a broom and then a Shop Vac. Seldom are the
inner components of the gear cleaned of dust, dirt, or debris. As
more electronics are pushed into this gear we need to change how it
is treated.
If you had the foresight to write
the cleanliness of these systems into the project scope, the
electrical gear would stay shrink wrapped until the rooms were clean.
But unless it is explicitly written into the contract, the cleaning
won’t be done because electronics are relatively new so it is not
yet customary to the trade work. Requiring this level of caution goes
well beyond customary protection from physical damage and the
elements.
These systems are not just the
contractor’s responsibility, however. I remember an instance when
the client refused to allow the contractor to pave the roadway around
the data center until the end of the project. As a result, despite
the contractor’s extraordinary best efforts, the dust kicked up by
all the construction vehicles permeated the entire facility including
the switch gear. In the end it cost the entire team (owner, designer,
contractors) time and money to take everything apart, clean it, and
put it all back together.
So as owners,
designers, contractors, vendors, and consultants, what are you doing
to address these ever-changing needs for continuous and reliable
monitoring? It appears that most everyone is getting it when it comes
to continuous power for the electronics but what about all the other
environmental issues such as heat, condensation, and cleanliness?
In the end the operational reliability is
only as good as the weakest link in the chain.
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