GE Power Quality Meter Series Instruction Manual page 270

A.1 PQM APPLICATION NOTES APPENDIX A
The diagram above shows an example of a PQM being used to totalize the energy from 4 other PQMs. PQMs
1 through 4 have each of their respective AUX1 relays configured for Pulse Output functionality (refer to the
A
Pulse Output PQM Application note for details, or the PQM manual). The Switch Common output from PQM#4
is fed to the common contact of the AUX1 relays on PQMs 1 through 4. The N/O contact of AUX1 for PQMs 1
through 4 will operate based upon the setup as described in the Pulse Output functionality section of the PQM
manual. The Totalized Pulse Input register of PQM#4 can be set to sum the counts from Switch Inputs 1
through 4, thus giving a total energy representation for the 4 metering locations. The count value for each
Pulse Input on PQM#4 can be set to match the Pulse Output Interval as programmed on each PQM. For exam-
ple, if PQM#1 had a Pulse Output Interval = 100 kWhr, and PQM#2 had a Pulse Output Interval = 10 kWhr,
then Pulse Input 1 on PQM#4 would have the Pulse Input Value set for 100 and Pulse Input 2 on PQM#4 would
have the Pulse Input Value set for 10.
Various operating parameters with regard to the PQM Switch Inputs must be taken into account. The PQM
Switch Inputs require a minimum 100 ms operation time to be detected. Therefore the Pulse Output Width
should be equal to or greater than 100 ms. The duration of the contact operation can be indefinite. The internal
Switch Input circuit of the PQM is itself switched on and off at the times when the PQM is reading the status of
the Switch Inputs. Monitoring the input to one of the PQM Switch Inputs will reveal a pulsed 24 V DC wave-
form, not a constant signal. Standard wiring practice should be adhered to when making connections to the
PQM Switch Inputs, i.e. avoiding long runs of cable along current carrying conductors or any other source of
EMI. An induced voltage on the Switch Input can cause malfunction of the Switch Input.
A-20 PQM Power Quality Meter GE Power Management