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For the signed power factor, use the following conversion formulas.
For positive (lagging) power factor:
I analog = 20 - PFmeasured × (20 - Zero_offset)/2
For negative (leading) power factor:
I analog = Zero_offset - PFmeasured × (20 - Zero_offset)/2
When I analog ≥ (20 - Zero_offset)/2:
=
PFmeasured
When I analog < (20 - Zero_offset)/2:
(
Zero offset
=
PFmeasured
4.11 Analog Expander Operation
The PM295 can provide extension of the internal analog output (up to 7 or 14
analog outputs) by using one or two external analog expanders AX-7. The AX-7 is
an external box, DIN rail mounted, that has seven current outputs (0 - 20/4-20 mA)
and is connected to the Powermeter via a RS-422 communications link. It can share
the same link with the master computer or PLC without interfering in their
operations.
The AX-7 can be located at distances up to 1200 meters away from the Powermeter
and close to the analog inputs of the PLC or other analog measuring device. For the
analog expander connection and operation, refer to publication "Analog Expander
AX-7. User' s Guide".
Each of the extended analog channels can be configured to output any parameter
provided by the PM295 for analog output, and can be scaled in the same manner as
the internal multiplexed analog output channels. When using two analog expanders,
the output channels #1 to #7 will correspond to the first analog expander, and
channels #8 to #14 - to the second one.
74
−
×
(
20
Ianalog
)
2
−
20
Zero offset
_
−
_
Ianalog
−
20
Zero offset
_
×
)
2
Operation Techniques
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