10.6 Voltage protection
10.6.1 Two step undervoltage protection UV2PTUV
Prepare the IED for verification of settings outlined in section "Preparing the IED to
verify settings".
10.6.1.1 Verifying the settings
Verification of START value and time delay to operate for Step 1
1. Check that the IED settings are appropriate, especially the START value, the
definite time delay and the 1 out of 3 operation mode.
2. Supply the IED with three-phase voltages at their rated values.
3. Slowly decrease the voltage in one of the phases, until the START signal
appears.
4. Note the operate value and compare it with the set value.
The operate value in secondary volts is calculated according to
the following equations:
For phase-to-earth measurement:
U UBase VT
VTprim
1
100
3
<
× ×
sec
IECEQUATION2430 V1 EN (Equation 94)
For phase-to-phase measurement:
U
UBase
VT
VTprim
1
100
<
× ×
sec
IECEQUATION2431 V1 EN (Equation 95)
5. Increase the measured voltage to rated load conditions.
6. Check that the START signal resets.
7. Instantaneously decrease the voltage in one phase to a value about 20% lower
than the measured operate value.
8. Measure the time delay for the TRIP signal, and compare it with the set value.
9. Check the inverse time delay by injecting a voltage corresponding to 0.8 × U1<.
For example, if the inverse time curve A is selected, the trip
signals TR1 and TRIP operate after a time corresponding to the
equation:
1MRK 506 355-UEN A Section 10
Testing functionality by secondary injection
Line distance protection REL670 2.1 IEC 171
Commissioning manual
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