Siemens 7SA511 manual Voltage-Controlled Overcurrent Fault Detection Test Optional

7SA511 Line Protection Relay Acceptance Tests

Test Procedure

The test current is increased gradually in any phase until the element picks up. The pickup current value is then verified against the programmed settings. Ensure that the relay picks up at 1.1 times the setting value and does not pick up at 0.9 times the setting value. The reset value should be 95% of the pickup value.

When testing phase-to-phase current, pickup indication appears for the associated phases. If the phase overcurrent threshold value is exceeded when testing phase-to-ground current, the pickup indication for ground current (IE>) appears for the tested phase. The factory preset indicators that are applicable in these cases are as follows:

LED 2 for overcurrent fault in phase 1

LED 3 for overcurrent fault in phase 2

￿LED 4 for overcurrent fault in phase 3 LED 5 for ground fault detection (IE>)

Trip delays are normally tested at two times the pickup current value. Depending on the voltage polarity, directional final time T4 (address 1203) or nondirectional final time T5 (address 1204) will apply. The set times are pure delay times; operating times of the measurement functions are not included.

Remove the input voltage. Repeat time measurement for one phase. Now, the trip delay for emergency backup operation is applicable:

TI> for phase currents - address 2604

￿TI>> for high-set phase currents - address 2606 TI> time for ground currents - address 2609

3.9.2Voltage-Controlled Overcurrent Fault Detection Test (Optional)

This test checks the operation of the optional voltage-controlled overcurrent fault detection function. The relay model number must be 7SA511*-**A52/3-**** for this test to be applicable. Testing requires the use of a three-phase voltage source and a single-phase current source. In this test, the three phase voltages are applied simultaneously to the voltage inputs while test current is applied sequentially to each of the four current inputs.

An example of the pickup characteristic is shown in Figure 3-1. With factory settings, the slope of the voltage-dependent branch is zero since the voltage settings for both the Iph> and Iph>> current levels are the same (i.e., 48 V for phase-to-ground voltage and 80 V for phase-to-phase voltage).

July 27, 1995 3-17