Protection based on internal Calculation
The UMC can detect an earth fault by summing up the three phase currents without using an external current transformer. The inter-
nal earth fault detection function signals a warning when the earth fault current exceeds a set threshold for a configurable period
of time, after the motor start-up. The earth fault detection function creates a trip when the current continuously exceeds a separa-
tely set threshold for a set period of time, after the motor start-up.
•
e
to be detected
• Only usable in networks with low impedance to ground.
Only higher ground fault currents can be detected
•
e
• In case of fast starting motors without load an earth fault trip can happen during the start-up phase. Configure a
delay time in this case.
Block Diagram:
—
Signal flow of the internal earth fault protection function
Relevant Parameters Internal Ground Fault:
• Earth Flt Trip Level • Earth Flt Warn Level
• Earth Flt Trip Delay • Earth Flt Warn Delay
• Earth Flt Detection
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