ABB Relion 620 Series - Page 915

Figure 492: Functional module diagram for calculating accumulative energy and
alarm
Accumulated energy calculator
This module calculates the accumulated energy I
y
t [(kA)
y
s]. The factor y is set with
the Current exponent setting.
The calculation is initiated with the POSCLOSE input opening events. It ends when
the RMS current becomes lower than the Acc stop current setting value.
Figure 493: Significance of the Difference Cor time setting
The Difference Cor time setting is used instead of the auxiliary contact to
accumulate the energy from the time the main contact opens. If the setting is
positive, the calculation of energy starts after the auxiliary contact has opened and
when the delay is equal to the value set with the Difference Cor time setting. When
the setting is negative, the calculation starts in advance by the correction time
before the auxiliary contact opens.
The accumulated energy outputs IPOW_A (_B, _C) are available in the monitored
data view on the LHMI or through tools via communications. The values can be reset
by setting the parameter Initial CB Rmn life setting to true in the clear menu from
WHMI or LHMI.
Alarm limit check
The IPOW_ALM alarm is activated when the accumulated energy exceeds the value
set with the
Alm Acc currents Pwr threshold setting. However, when the energy
exceeds the limit value set with the LO Acc currents Pwr threshold setting, the
IPOW_LO output is activated.
1MRS757644 H
Condition monitoring functions
620 series
Technical Manual
915