Chapter 3 - Device Overview
44 3BHS335648 E82 UNITROL 1020 User Manual
3.4.2.3 Boost / Voltage Relay
- Pick-up volt. to
generate boost
command
- Time boost
output is active
- Hysteresis for
the reset of
boost output
- Delayed OFF
- Boost on grid
only
- Block boosting
in case of PT
alarm
Threshold [%]
Hold Time [s]
Hysteresis [%]
Delay time [s]
Check box
Check box
[s]
Excitation ON
not active
Boost =
Voltage Relay= 1 0
0
1
1
0
0
1
Voltage
drop
Hysteresis
Machine voltage
Excitation ON
Soft start
100%
t
Threshold
1
Hold time
0
Delayed
Off
1
Hold Time = Maximum active Boost Time
Boosting is disabled if “Block boosting in case of PT alarm” parameter is selected and any
of the following failures is detected.
Failures: a) Partial Loss of UM
b) Loss of UM
Current boost operation is canceled when either failure is detected
Detection of PT failures relies on Supervision functions (status, not latched), PT failures
will only be detected when the DCH SW option is enabled
Note that Voltage Relay operates independently of the status of Excitation ON.
3.4.2.4 Forcing PWM to maximum
In order to make boosting independent of PID settings, PWM output can be driven to the
maximum value in case of undervoltage detection. This function is enabled by the
parameter “Maximum PMW when Boosting”.
The function is parametrized by the normal boost setting and on off timing is also
considering actual SP.
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