Fast Load Shed Trigger Logic; Over Current Based Load Shed - ABB RELION 630 Series Technical Manual

Section 7
Power management functions
7.4.4.5
7.4.4.6
222

Fast load shed trigger logic

This module calculates the fast load shed trigger to initiate the load-shedding action.
CB_POSITION
CB_LOCK_OUT
CB_SERVICE
INHIBIT_TRG
Load-shedding
blocking
(From Block logic module)
GUID-45962C27-4CCB-4848-9F22-2B31A9656464 V1 EN
Figure 134: Fast load shed trigger logic
If the BLK_BYPASS output is active, FLS_TRIGGER remains
FALSE.
The output FLS_TRIGGER (fast load-shedding trigger) is provided to the Binary to
integer module.

Over current based load shed

This module calculates the slow load-shedding start and slow load-shedding trigger
based on the phase overcurrent detection of the power source or external trigger input
activation.
The Slow load shed mode setting enables or disables the Over current based load shed
module. If the Slow load shed mode setting is "OC & Ext Trg " or "OC, Max Dmd, Ext
Trg", the Over current based load shed module is enabled, else it is disabled.
This module compares the effective start value to the maximum of the I_A, I_B, I_C
inputs.
If the input ENA_MULT (enable start value multiplier) is TRUE, the effective start
value is the product of the Start value and Start value Mult settings, else the effective
start value is same as the Start value setting.
If the maximum of the I_A, I_B, or I_C inputs is greater than the effective start
value, the output OC_STR (overcurrent start) is TRUE, else the output OC_STR is
FALSE. The maximum of the I_A, I_B, or I_C input is provided as the
MAX_CURRENT output. The effective start value is provided by the PICKUP output.
If the phase overcurrent is detected, the output OC_TIME (overcurrent operating time)
is calculated as per the Operating curve type setting. After the operate time, the
OC_OPR output is TRUE.
Close
Open
Intermediate
OR
Open
1
0
PML630/Compact Load-Shedding Solution
1MRS757256 F
AND FLS_TRIGGER
Technical Manual