TSC 900 TRANSFER SWITCH CONTROLLER
PM 151 REV 1 15/10/08 Thomson Power Systems
5.13.1. LOAD VOLTAGE BLACKOUT DELAY (DROPOUT)
Select the desired source load voltage blackout time delay setting. The setting is
entered in seconds. If no delay is required, set this time delay to zero.
5.13.2. LOAD VOLTAGE BLACKOUT DROPOUT
This set point is utilized for neutral delay bypass and transfer fail logic. Set to the
desired load voltage blackout drop out set point as expressed in percentage of nominal
system voltage. The drop-out set point is the value which the internal sensor de-
energizes to an abnormal state when any one phase of the load voltage falls below the
set point. A blackout voltage condition will be triggered following expiry of the load
voltage time delay setting.
5.13.3. LOAD VOLTAGE BLACKOUT PICKUP
This set point is utilized for neutral delay bypass and transfer fail logic. Set to the
desired load voltage blackout pick-up set point as expressed in percentage of nominal
system voltage. The pick-up set point is the value which the internal sensor energizes
to a normal state when all phases of the load voltage rises above the set point.
5.14. LOAD SHED SET FREQUENCY & POWER POINTS
The TSC 900 controller provides Frequency and Power (kW) sensing on the load of the ATS
for purposes of controlling the automatic Load Shedding feature. To enable these features,
refer to Option settings per Section 5.10.3 and Section 5.10.4 Load shed can be configured
to operate when set points have been reached on bus under frequency and/or bus over power
(kW) conditions. When a load shed condition is activated, an alarm will be posted on the GHC
display and a programmable output configured for Load Shed will be activated to control an
external system load to be automatically disconnected. Each load bus sensor is individually
programmable for pickup and dropout set points (i.e. adjustable hysteresis) in addition to
transient time delay settings. Refer to Section 3.4 for further details on automatic load shed
sequence of operation.
NOTES:
1. Load Shed operation based on Power (kW) is only available if
the ATS is equipped with CT’s on the load side of the ATS and
Power Metering operation is enabled.
2. Automatic load shed operation on either bus under frequency
or bus over power will only occur when the TSC 900 controller
Mode is set for “AUTO”. When the TSC 900 controller Mode is
set for “MANUAL or OFF” the load shed relay will not operate.
To program the sensing features, refer to the following descriptions:
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