Tests; Inspection; Secondary Injection Tests; Primary Injection Tests - Siemens 7SR23 DAD Manual

High impedance protection relay

1.3

Tests

1.3.1

Ensure that all connections are tight and correct to the relay wiring diagram and the scheme diagram. Record any

deviations. Check that the relay is correctly programmed and that it is fully inserted into the case. Refer to

'Section 2: Settings and Instruments' for information on programming the relay.

1.3.2

Select the required relay configuration and settings for the application.

Isolate the auxiliary D.C. supplies for alarm and tripping from the relay and remove the trip and intertrip links.

Carry out injection tests for each relay function, as described in this document

For all high current tests it must be ensured that the test equipment has the required rating and stability and that

the relay is not stressed beyond its thermal limit.

1.3.3

Primary injection tests are essential to check the ratio and polarity of the current transformers as well as the

secondary wiring. Primary injection testing of the 87/50 Differential protection is recommended to avoid relay

operation during first energisation of the busbar if circuit connections have been incorrectly installed.

Differential current flowing in the relay circuit can be checked by examination of the relay Current Meters in the

Instruments Menu when the protected plant is carrying load but Earth Fault CT polarity can only be checked

during primary injection.

1.3.4

After tests have been performed satisfactorily the relay should be put back into service as follows:-

Remove all test connections.

Replace all secondary circuit fuses and links, or close m.c.b.

Ensure the Protection Healthy LED is on, steady, and that all LED indications are correct. If necessary press

CANCEL until the Relay Identifier screen is displayed, then press TEST/RESET to reset the indication LEDs.

The relay meters should be checked in Instruments Mode with the relay on load.

The relay settings should be downloaded to a computer and a printout of the settings produced. The installed

settings should then be compared against the required settings supplied before testing began. Automated setting

comparison can be carried out by ReyDisp using the Compare Settings Groups function in the Edit menu. Any

modified settings will be clearly highlighted.

Chapter 6) 7SR23 DAD Commissioning & Maintenance Guide

Chapter 6 Page 8 of 26

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