Signals - ABB RELION 620 Series Technical Manual

1MAC504801-IB E
4.4.5.6
620 series ANSI
Technical Manual
typically set to operate when the current into a motor lags more than 30 degrees, that is, a
power factor goes below +0.87 lagging.
The function provides alarm facility which can be used as an early indication that the
power factor is moving outside the allowable range; therefore the Alarm value setting
should be set higher than the Pickup value. The delay time for alarm should also be set as
low as possible, only long enough to prevent spurious activation of the output.
In a power factor correction application, the ALARM and PICKUP outputs can be used as
controls to switch in capacitive loads when the Alarm value and Pickup value settings,
respectively, are exceeded. The ALARM output is set for a higher value to add the first
corrective load and the PICKUP output set for a second stage of corrective load, if needed.
The Pickup reset value and Alarm reset value settings allow their respective outputs to
remain activated to maintain the correction after power factor rises as a result, but to drop
out after it reaches a level where corrective capacitive loading is no longer needed.
There are two general applications which can best utilize under power factor protection;
power-factor control and loss of excitation.
When applying the function for power-factor control, both the pickup value and the
pickup reset value should be the same sign (positive/negative) as well as the same
direction (leading/lagging). Additionally, the absolute value of the pickup reset value
should be greater than or equal to the absolute value of the pickup value. This allows the
function to properly control any power factor controls within the system.
When applying the function for loss of excitation, both the pickup value and the pickup
reset value should be the same sign (positive/negative), but the directions should be
different (leading/lagging). This application is well-suited to protect against back-
spinning. In this case the pickup reset value will only come into play once the system
provides power in the opposite quadrant of the pickup value, for example, lagging PF turns
to leading PF.

Signals

Table 306: 55 Input signals
Name Type
I_A SIGNAL
I_B SIGNAL
I_C SIGNAL
V_A SIGNAL
V_B SIGNAL
V_C SIGNAL
DISABLE BOOLEAN
BLOCK BOOLEAN
Default Description
0.0 Phase A current
0.0 Phase B current
0.0 Phase C current
0.0 Phase to earth voltage A
0.0 Phase to earth voltage B
0.0 Phase to earth voltage C
0=False Signal to block the function during machine startup
0=False Block signal for activating the blocking mode
Section 4
Protection functions
371