Introduction

The GE Multilin 515 Blocking and Test Module has the following features:

• 14 Pole switchbank

• CT inputs short when current switches are opened

• Current injection for each phase

• Ground terminal

• Ability to visually isolate (open) trip relay output circuits

• Cover provided

• Suitable for utility and industrial use

• 515 test plugs available

Description

The 515 Blocking and Test Module provides an effective means of trip blocking, relay isolation and testing of GE Multilin relays. By opening the switches and inserting test plugs, phase and residual currents from the primary CTs can be monitored. Currents can be injected into the relay from a secondary injection test set during commissioning.

Prior to testing, the trip and auxiliary circuits must first be opened to prevent nuisance tripping; CTs can then be shorted. Conversely, when the test is complete and the relay put back into operation, the CT switches should be closed first to ensure normal operation of the relay, prior to closing the trip and auxiliary circuits.

Installation

Shorting switches are provided for connection of 3 phase CTs (current transformers) and a separate core balance ground fault CT or 3 phase CTs connected for residual ground fault sensing.

When each CT switch is opened, the CT is shorted. It is essential that the CT is connected to the shorted side of the switch as shown in the following figure, otherwise dangerously high voltages would be present from the open circuited CTs.

When the switches are open, test plugs can be inserted to either inject signals into the relay wired to the switches or monitor signals such as CT current from the switchgear.

The 515 Blocking and Test Module consists of a metal chassis attached to the 515 test switches that slides into the panel. A single cutout in the panel, as per the dimensions shown in Figure 3, is required to mount the 515 test switches.