SATEC EM920 Operation Manual - Manual (Page 91)

Chapter 5 Configuring the EM920
General Meter Setup
EM920 Power Quality and Revenue Meter 91
When you select an output parameter for the analog output
channel, the default engineering scales are set automatically.
They correspond to the maximum available scales. If the
parameter actually covers a lower range, you can change the
scales to provide a better resolution on an analog output.
Scaling Non-Directional Analog Outputs
For non-directional analog outputs with a 0-1mA, 0-20mA or
4-20mA current option, you can change both zero and full
engineering scales for any parameter. The engineering scale
need not be symmetrical.
Scaling Directional Power Factor
The engineering scale for the signed power factor emulates
analog power factor meters.
The power factor scale is -0 to +0 and is symmetrical with
regard to ±1.000. The negative power factor is scaled as
-1.000 minus the measured value, and non-negative power
factor is scaled as +1.000 minus the measured value. The
default scales are set to -0.000 to 0.000 to specify the full
power factor range.
Scaling ±1mA Analog Outputs
Engineering scales for directional ±1mA analog outputs
depend on whether the output parameter represents an
unsigned (as volts and amps) or signed (as powers and
power factor) value.
For an unsigned output value, you can change both zero and
full engineering scales.
For a signed (directional) value, you should only provide the
engineering scale for the +1 mA output current.
The engineering scale for the 0 mA output current is always
equal to zero for all values except the signed power factor,
for which it is set to 1.000 (see
Scaling Directional Power
Factor above).
The meter does not allow changing the low scale setting if the
parameter is directional. Whenever the sign of the parameter
is changed to negative, the meter automatically uses the full
engineering scale setting for +1 mA with a negative sign.
Scaling Analog Outputs for 0-2 mA and ±2 mA
The 0-1mA and ±1mA outputs provide a 100% overload, and
actually allow currents up to 2 mA and ±2mA whenever the
value exceeds the engineering scale for 1 mA or ±1mA.
The output scales for 0-1 mA and ±1 mA analog outputs are
programmed for 0 mA and +1 mA regardless of the required
output current range.
To use the full output range of 2 mA or ±2 mA, set the
analog output scales as follows:
• 0-2 mA: set the 1 mA scale to ½ of the required full
scale output for uni-directional parameters, and set