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D-500 MK2 User Manual
32.3. OVER/UNDER FREQUENCY FUNCTION
This protection function measures the frequency of the mains for each period. If the frequency is outside
limits for 4 successive periods, it detects a mains failure. The response time of the mains frequency is
approximately 4 cycles.
Related parameters:
Mains Frequency Low Limit
Mains Frequency High Limit
32.4. OVER/UNDER VOLTAGE FUNCTION
The mains phase voltages are measured twice a second and compared with predefined high and low
limits. If at least one of the phase voltages is outside limits, this will mean a mains failure. The response
time is approximately 500ms.
Related parameters:
Mains Voltage Low Limit
Mains Voltage High Limit
32.5. MAINS REVERSE POWER FUNCTION
The mains active power is measured for each period. If the genset system supplies power to mains and
this power exceeds the predefined limit, this will mean a mains failure.
The mains reverse power detector has a variable response time. For a power not exceeding 2 times the
predefined limit the response time is 8 cycles. The response time is reduced with larger reverse powers. It
is approximately 1 cycle with a reverse power of 8 times the predefined limit.
Related parameter:
Mains Reverse Power Limit
If the parameter is set to zero, then the protection function will be disabled.
32.6. NO FREQUENCY FUNCTION
The unit counts the time after the last detection of the mains frequency pulses. If no mains pulses is
detected for a period corresponding to 2,5 times the Mains Frequency Low Limit, a mains failure alarm
is generated.
Related parameter: Mains Frequency Low Limit
If the parameter is set to zero, then the protection function will be disabled.
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Firmware V-6.3
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