SATEC EM720 Operation Manual - Manual (Page 23)

Chapter 2 Operating the EM720
Operating Relay Outputs
EM720 Power Quality and Revenue Meter 23
LED Color Status Description
IN1, IN2 Yellow Lights The digital input terminals are shorted
OUT1, OUT2 Green Lights The normally open relay contacts are closed
Fast internal digital inputs are sampled at a 1-ms rate, and
expansion inputs are sampled at a 1/2-cycle rate.
Digital inputs functionality is programmable in the EM720 and
any digital input can perform multiple metering and control
functions at the same time:
• Receiving energy pulses from external watt meters
(sub metering) – link a digital input to a Billing/TOU
register and provide a required multiplication factor
(see
Configuring Billing/Tariff Registers in Chapter 5)
• Counting pulses from external pulse sources – link a
digital input to a pulse counter (see Using Counters in
Chapter 5)
• Triggering a setpoint – put a digital input into a
setpoint trigger list (see Using Control Setpoints in
Chapter 5)
• Triggering the Fault Recorder – link a digital input to
the Fault Recorder (see Configuring Digital Inputs in
Chapter 5) and enable external triggers in the Fault
Recorder setup (see
Configuring the Fault Recorder in
Chapter 5)
• External synchronization of power demand intervals –
select a digital input as an external power demand
sync source (see
Basic Meter Setup in Chapter 5)
• External synchronization of the meter clock – select a
digital input as a time synchronization input (see Local
Settings in Chapter 5) and provide minute-aligned
pulses from the external master clock source.
All digital inputs have a user-programmable debounce time
from one to 100 milliseconds. See
Configuring Digital Inputs
in Chapter 5 on how to configure digital inputs in your meter.
Operating Relay Outputs
Up to four relay outputs can be provided in your EM720 with
two expansion 2-channel 2DI/2DO replaceable modules. See
the EM720 Installation Manual for available relay output
ratings and connections.
See Section Operating Digital Inputs above for the relay
terminals location and relay status LED indicators.
All relay outputs are updated at a half-cycle rate.
Each relay is independently programmable in the EM720 and
can operate in latched, unlatched, pulse or KYZ mode.
Relay operations can be inverted so that the relay is
energized in its non-active state and de-energized when it is
operated. This mode, known as “failsafe” mode, may be used
for signaling purposes to send alarms when the device is not
operational either due to a fault or due to loss of power.
R1
R2
1
C
2
C
2DI/2DO M ODULE