Monitoring the site power
the plots
plot
description
programs used for
monitoring
Site power
documentation
Monitoring the site power
A programmable breaker (ABB eVD4) was
installed in the power substation in mar13. This
breakersmeasures the power, voltage, currents .. at the input
to the substation. The information is queried and written to
disc once a minute. At 7:10 am every morning plots are made of
the power usage from the last 7 days. Once a month plots are
made for the entire month:
The plots:
Power substation plots
for the last 7 days (.ps) (.pdf):
Monthly substation
plots
year
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jan
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Feb
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mar
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apr
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may
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jun
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july
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aug
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sep
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oct
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nov
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dec
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2013
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(.pdf)
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(.pdf)
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Plot description:
The plots are made once a day (at 7:10 am).
The data is sampled once a minute. The frames in
each plot are:
- Frame 1: power (Kilowatts)
- white: apparent power (Kvolts*Iamps) at input
- red: active power. This is the power used to do work.
- The plot is -Active power. The convention is an
inductive load is negative, a capacitive load is
positive
- blue: minus the Reactive power
- Frame 2: Power factor:
- Active Power/Apparent power. It is negative since the
load is inductive.
- Frame 3: Current (amps)
- white: phaseA, red phaseB, blue phaseC
- solid line (what breaker calls instantaneous power)
- This looks like it has a threshold for measurement.
When the current changes by a certain amount a new value
is recorded.
- dashed line: 1 minute demand current provided by
breaker. Not sure whether this is a max or average.
- Frame 4: Phase to Phase voltage (Kilovolts)
- white phaseAtoB, red phaseBtoC, blue phaseCtoA
- Frame 5: Phase to ground Voltage (Kilovolts)
- white: phaseA, red phaseB, blue phaseC.
- Notes on the measurements
- The values reported by the browser screen
differ from these values by 1 or 2 %.
- The browser shows two types of values:
_INST_ and _DB_. I think the _DB_ values have been
corrected.
- The analog input configuration section shows
some correction factors (.1 to 1.2%) for some
measurements (errors in a/d ?).
- I tried applying these corrections to the
_INST_ data and got values that were closer but not
exactly the same as those reported on the measurement
screen of the browser.
- In the end, the values shown in the plots have
not had any corrections made to them. they are the
_INST_ values from the breaker.
Programs used for the
monitoring:
- /share/megs/phil/svn/aosoft/src/sitepwrlog.c
- Program to read the breaker and output the data
- Writes to /share/phildat/sitepwr/sitepwr_yyyymmdd.dat
- This program runs on aserv11. If the computer reboots it
will probably have to be restarted (via)
- /share/megs/phil/svn/aosoft/src/sitepwrlog &
- Making the plots:
- /share/megs/phil/x101/sitepwr:
- sitepwrdaily.sc script run via phil's
crontab on megs3 to make the daily plots
- sitepwrdaiily.pro idl code to make the plots