User's Manual
58 Meter Operation
same time. When the maximum random number of seconds is set to 0 (zero), the
relay will close immediately.
The control relay is a single-pole single-throw normally-open (1P-1T NO) dry (no
output voltage) switch. The maximum load rating is 5A. Voltages above 40V, but not
exceeding 250V can be routed through the relay.
Note: The control relay is not fully electrically isolated in regard to certain safety
considerations. It is physically isolated.
Display Indicator for Control Relay Position
This display indicator is illuminated when the control relay is in the open
position.
Remote Relay Status
The OFF (open) or ON (closed) status of the control relay can be determined remotely
via NES System Software, or locally via the Provisioning Tool.
LED Pulse OutputFor accuracy verification the meter has 2 infrared LED pulse
outputs that blink at the rate of energy consumption for both active (kWh) and
reactive (kvarh) energy. The rate is 1,000 impulses per kWh or kvarh. These LEDs
can be read by test and calibration equipment.
Pulse Output Signal (KYZ)
An optional pulse output (KYZ) can be provided via a cable. The pulse rate is user
definable with a range of 1 to 1000 pulses per kWh. A typical setting is 1000 pulses
per kWh. The pulse width is user definable with a range of 10 to 500 milliseconds.
The KZ pulse output parameters are interlinked in that incorrect choices for these
parameters can cause saturation of the pulse output before reaching the maximum
power of the meter. As the pulse rate is increased, the pulse width must be
decreased. For example, a pulse rate of 1,000 is compatible with a pulse width of
30ms. However, a pulse width of 100ms will not allow correct operation in a 3-phase
meter.
The following formula provides the maximum pulse width that would cause
saturation exactly at maximum power (100% duty-cycle). For proper operation and
also dependent on the device to be connected to the KZ pulse output, a percentage of
this time should be used. For example, for a 50% duty cycle at maximum power, the
maximum pulse width must be divided by 2.
Maximum pulse width = (3.6 x 10
9
) / (MP x PR)
where:
PR = pulse rate
MP = maximum power = “rated voltage” x “maximum current” x “number of phases”