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Generation · Transmission

Three Phase Control Wiring

Contactors and control wiring

This three-phase control wiring training course introduces basic safe operational aspects of electrical wiring in grid substations.

Step by Step Guide for Console box control wiring

  • Step-1 Fix the channels as per the width of Terminal blocks.
  • Step-2 Fix the Terminal Blocks as per the requirement
  • Step-3 Dressing the cable terminations.
  • Step-4 Check for continuity of the cable
  • Step-5 Start ferrule as per standards.
  • Step-6 Insert the lugs and do the crimping properly
  • Step-7 Tighten the lugs in the TB as per the connection diagram.

step-1

DIN rails and slotted ducts on an empty control-panel backplate

Step -2

There are two types of TB

  1. Stud Type

2. Disconnecting type

The disconnecting type TBs are here in the picture shown below.

Knife-disconnect terminal blocks on a DIN rail

Step 3

Cable Dressing & Terminations:

Cable terminations make physical and electrical connections between the cable and the terminal of the equipment, junction, or another cable, thereby facilitating the flow of electricity in the desired manner.

Cable terminations play an important role in the proper functioning of the cable and the equipment to which it is connected.

Cable dressing ensures that terminations are neatly arranged with the help of  Cable ties, cable channels, and glands.

Step 4

Check the continuity of the cable with the help of a multimeter.

Step 5

Here for fixing the cable number and CRP (Control Relay Panel) box number ferrules are used. On this ferrule mark, the endpoints of cables is done that has to be installed between CRP to CT Console Box panel in AIS.

Numbered ferrule markers on loose control wires
TypeDescription
Start FerruleThe internal ferrules used in the CONTROLLING Equipment to be provided on both ends of the wire e.g. for remote controlling the CB the internal ferrule at the control panel to be used on the controlling wire
End ferruleThe internal ferrules used in the CONTROLLED Equipment to be provided on both ends of the wire e.g. for remote controlling the CB the internal ferrule at the BREAKER CUBICLE to be used on the controlling wire

Ferrule System

Letters used in the Ferruling Scheme

LettersPurposeLettersPurpose
ACT SEC Main ProtectionLAlarm, Indication, Annunciation circuit
BBus Bar ProtectionMMotor Control Circuit
CBack up ProtectionNTransformer Tap Changer Control Circuit
DCT Metering CircuitPPower Cable Identification
EPT/CVT secondary circuitQEquivalent Control Circuit
FFan Control CircuitSEvent logger/DAS/SCADA circuit
GPT Synchronising CircuitTTerminal Identification Circuit
HLT AC SupplyUUsed for spare contacts
JDC Main CircuitXUsed for spare wires
KDC Control Circuit

FERRULING SCHEME

Step -6 Crimping Tool and other accessories for wiring

here one can see various tools required for console box wirings such as screwdrivers and crimping tools.

Crimping tool, wire ferrules and wiring accessories

Step 7

The stud, washers, nuts, locknuts, and inserts shall be tin-plated Brass. Terminal block design shall include markings of terminals and the terminals shall be provided with transparent plastic, slip-on/clip-on terminal covers. Markings on the terminal strip shall correspond to the wire number and terminal numbers on the wiring

Wire colors for internal wiring

Color of WiresPurpose
REDPhase connection is either directly connected to the primary circuit or secondary circuit of CT or PT
YELLOWPhase connection is either directly connected to the primary circuit or secondary circuit of CT or PT
BLUEPhase connection is either directly connected to the primary circuit or secondary circuit of CT or PT
BLACKStar point connection of secondary circuit of CT and PT
GREENConnection to earth
GREYConnection in DC Circuit