ABB RELION REX640 Technical Manual page 252

Section 3
Basic functions
246
COUNT_VALUE activation, READ_VALUE also activates output VALUE_READ for
200 ms.
The activation of RESET resets COUNT_VALUE to zero. Activation of
FREEZE_COUNT freezes further counting.
Changing Count criteria does not reset COUNT_VALUE.
Scaling
This module scales the count value available at COUNT_VALUE. The scaling
depends on the Unit selection setting. When the function is used for general-purpose
counting, Unit selection is set as "Count" and the count value is multiplied by the Pulse
quantity setting to calculate the scaled value.
When using this function for energy measurement, Unit selection is set accordingly,
that is, real, active or apparent energy and the count value is divided by Impulse ratio
to calculate the scaled value. The prefix for unit of Impulse ratio is defined by setting
Impulse ratio prefix.
The energy meter defines the impulse ratio (also known as meter
constant), that is, it indicates the number of pulses the meter generated
per kWh (or MWh). Impulse ratio must be set based on the energy
meter used.
For example, if the impulse ratio is 100 impulses / MWh, set Impulse
ratio as 100 and Impulse ratio prefix as Mega.
If the impulse ratio is 800 impulses / KWh, set Impulse ratio as 800
and Impulse ratio prefix as Kilo.
The scaled value is available at SCALED_VALUE in the Monitored data view. This
output is updated cyclically and sent to the station HMI over various communication
protocols depending on Reporting interval setting. The start of Reporting interval
corresponds to the start of the function operation in the protection relay.
The activation of RESET resets SCALED_VALUE to zero.
If Pulse quantity, Impulse ratio or Impulse ratio prefix is changed in
between, SCALED_VALUE is updated immediately based on the
new setting.
Binary output VALUE_READ activates for a fixed 200 ms each time the reporting
timer completes its cycle.
It is also possible to update SCALED_VALUE before completion of Reporting
interval and make it available for communication by providing a pulse at
READ_VALUE input. The pulse width should be greater than 1 s. Besides updating
1MRS759142 C
REX640
Technical Manual