NG CH 20 PDF

PURPOSE

The purpose of this procedure is to provide a model process to detail the checks and tests to be performed when undertaking a settings loading verification test. It specifies the minimum requirement and may be added to by the contractor or NG Commissioning Engineer when devising test programmes. These checks and tests are designed to ensure that:

• The test highlights any incorrectly set relay, any incorrectly enabled functionality (e.g. stages of overcurrent within a multifunction relay) which may impinge on the load carrying capability of the circuit. The test will also highlight any relay rating or interpose CT error, which may be incorrectly limiting the primary circuit’s load carry capability.

• The test is also designed to confirm the circuit's secondary loading capability with a view to verifying that there is no conflict with the statements made to Operations and Trading on the Thermal rating Schedules submitted prior to energisation.

• The test is not designed to highlight any incorrect functionality that may be present that relates to a fault current condition i.e. an incorrect overcurrent setting that is well above load but operates incorrectly for an ‘out of zone’ system fault. This should be highlighted during stage 1 relay secondary injection testing as defined by SCT procedures.