Other Protection Functions
The following other protection functions are available with the MicroLogic P trip unit.
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Reverse power
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Minimum frequency
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Maximum frequency
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Phase rotation
The other protection functions are set using the keypad. The settings are listed in Threshold and Time-Delay Settings.
Operating Principle
Protection tripped by a minimum value |
Protection tripped by a maximum value |
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pickup threshold
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pickup time delay
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dropout threshold
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dropout time delay
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For protection tripped by a minimum or maximum value, it is possible to set:
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A pickup threshold (1) that activates an alarm, a contact and/or tripping.
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A pickup time delay (2) that steps in when the pickup threshold (1) is reached.
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A dropout threshold (3) corresponding to deactivation of the alarm and/or contact.
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A dropout time delay (4) that steps in when the dropout threshold (3) is reached.
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For protection tripped by a minimum value, the dropout threshold is always greater than or equal to the pickup threshold.
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For protection tripped by a maximum value, the dropout threshold is always less than or equal to the pickup threshold.
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If both the minimum and maximum protection functions are activated at the same time, the minimum threshold is automatically limited to the value of the maximum and vice versa.
Reverse-Power Protection rP Max
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This function calculates the value of the total active power on the three phases.
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The function is activated when the total active power of the three phases flows in the direction opposite to the one set by the user and is greater than the pickup threshold (1) for a time greater than the time delay (2).
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+ corresponds to the normal direction of flow, i.e. from the top terminals on the circuit breaker to the bottom terminals.
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- is the opposite.
Minimum and Maximum-Frequency Protection F min and F max
These functions monitor the value of the frequency on the distribution system.
Phase-Rotation Alarm
This alarm is activated if two of the three phases are inverted.