CHAPTER 1: OVERVIEW STANDARD FEATURES
PQM POWER QUALITY METER – INSTRUCTION MANUAL 1–7
d) Control Option
An additional three dry-contact form “C” output relays and four dry-contact switch inputs
are provided. These additional relays can be combined with setpoints and inputs/outputs
for control applications. Possibilities include:
• undercurrent alarm warnings for pump protection
• over/undervoltage for generators
• unbalance alarm warnings to protect rotating machines
• dual level power factor for capacitor bank switching
• underfrequency/demand output for load shedding resulting in power cost savings
• kWh, kvarh and kVAh pulse output for PLC interface
• Pulse input for totalizing quantities such as kWh, kvarh, kVAh, etc.
FIGURE 1–6: Switch Inputs and Outputs Relays
e) Power Analysis Option
Non-linear loads (such as variable speed drives, computers, and electronic ballasts) can
cause unwanted harmonics that may lead to nuisance breaker tripping, telephone
interference, and transformer, capacitor or motor overheating. For fault diagnostics such
as detecting undersized neutral wiring, assessing the need for harmonic rated
transformers, or judging the effectiveness of harmonic filters, details of the harmonic
spectrum are useful and available with the power analysis option.
DCS
RS485
MODBUS
4
RELAYS
ALARM
AUX 1
AUX 2
AUX 3
4
SWITCH
INPUTS
823775A7.DWG
PQM
Courtesy of NationalSwitchgear.com
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