Chapter 2 Operating the EM720
Billing and Energy Metering
18
EM720 Power Quality and Revenue Meter
You can monitor the status of batteries from the front display
on the Device Info pages (see
3) and via the device diagnostics.
The auxiliary battery voltage is about 8.2 volts at full charge
(for at least 20 hours). If it falls below, then the battery
should be checked.
When the lithium battery voltage drops below the minimum
allowed level, it is indicated by the blinking “Battery Low”
icon on the display and via the device diagnostics. In this
event, the battery should be checked and replaced if
required.
NOTE
Always clear the battery operation time counters after
replacing a battery. See
Resetting Accumulators and Clearing
in Chapter 6 for information on how to clear the
operation counters in your meter.
Billing and Energy Metering
The EM720 provides true four-quadrant energy
measurements with Class 0.2S IEC 62053-22 accuracy. The
following energy quantities are available for instrumentation
and billing:
•
kWh import (Q1+Q4)
•
kWh export (Q2+Q3)
•
kWh net (Q1+Q4)-(Q2+Q3) - instrumentation
•
kvarh import (Q1+Q2)
•
kvarh export (Q3+Q4)
•
kvarh net (Q1+Q2)-(Q3+Q4) - instrumentation
•
kvarh Q1, Q2, Q3, Q4 quadrants
•
kVAh import (Q1+Q4)
•
kVAh export (Q2+Q3)
•
kVAh total (Q1+Q2+Q3+Q4)
Energy Measurement Channels
The EM720 uses two independent current channels for high-
accuracy energy measurements and for conventional high-
range instrumentation. They have different gain and
measurement ranges as necessary for billing accuracy energy
metering and for power quality and fault monitoring.
1-second currents and powers provided by the meter and the
corresponding engineering display readings are taken from
the energy measurement channel. They begin measurements
from 5 mA starting currents and up to 10 A RMS with 5 A
secondaries, while instrumentation currents provide
measurements up to 50 A RMS.
