Figure 4.1 Example of alarm levels for busbar voltage
70
Voltage [% of nominal voltage]
Delay [s]
80
95
1 20 4 53
105
115
100
Over-voltage 2
Under-voltage 2
No voltage alarms
Over-voltage 1
Under-voltage 1
If the operation is in the green area, the controller does not activate any busbar voltage alarms.
In the example, an over-voltage Warning alarm is activated if the busbar voltage has been over 105 % of the busbar's nominal
voltage for 5 seconds. If the busbar voltage is over 115 % of the nominal voltage for more than 3 seconds, the controller activates
the Trip [Breaker] alarm action. Both alarms will be active if the busbar voltage is over 115 % of the nominal voltage for more than 5
seconds. The alarm action Trip [Breaker] has a higher priority than Warning.
The graph shows two protection levels for under-voltage. In the example, if the busbar voltage is under 95 % of the nominal voltage
for more than 5 seconds, a Warning is activated. If the busbar voltage is under 80 % of the nominal voltage for more than 3 seconds,
the Trip [Breaker] alarm action is activated.
4.1.3 Operate time
The operate time is the total time that the controller takes to respond to a change in the operating conditions. The operate time is a
controller characteristic, and not a configurable parameter.
The controller operate time is listed for each AC protection. The operate time starts when the AC conditions change so that the
alarm set point is exceeded. The operate time is completed when the controller has changed its output(s) accordingly.
Operate time = measurement time + calculation time + time to change the controller output(s)
For example, the operate time may be "< 100 ms". This means that the controller protection responds to the change in the
alternating current conditions within 100 ms.
INFO
The operate times do not include any provision for the time delay configured for the AC protection. For example, over-
voltage has an operate time of < 100 ms, but the default time delay for Over-voltage 1 is 5 seconds. The Over-voltage 1
alarm action is therefore between 5.0 and 5.1 seconds after the alarm set point is exceeded.
4.1.4 Customising alarms
You can customise the alarms for your system by configuring the alarm parameters. The parameters that you can configure are
restricted for some alarms.
More information
See Alarms, Alarm parameters for more information about parameter settings.
DESIGNER'S HANDBOOK 4189340911K UK Page 93 of 521
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