Specific Installation Instructions

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Polarity Markings

 

Most Hobut CTs are labelled as per IEC61869-2 using the P1 – P2: S1 – S2 nomenclature, the table below gives cross reference to some common alternative terminal marking standards.

Standard Primary Secondary
IEC61869-2 P1 P2 S1 S2
IEEE C57.13 H1 H2 X1 X2
K L k l

 

CTs with multiple secondary ratios will be marked S1,S2,S3….

CTs with multiple cores or windings will be marked 1S1,1S2 (first core secondary connections 1 and 2) 2S1, 2S2 (second core secondary connections 1 and 2) and so on

Always follow the polarity markings on the CT, as a standard Hobut CTs are constructed as follows. Please be aware that this can change for bespoke CTs, CTs with multiple windings and by customer request.

Moulded case CTs

Polarity markings are moulded into the case. Facing the CT on the P1 side, S2 will be the left hand terminal, S1 will be the right hand terminal.

Ring Type CTs

Polarity markings are applied onto the CT after construction. Facing the CT on the P1 side, S2 will be the left-hand terminal, S1 will be the right-hand terminal.

 

CTs with Cable Connection

Some CTs most often ring type CTs and split core CTS come with cabled connections, for CTs with more than 2 wire you must refer to the labels.

P1 will be marked on the CT label. For CTs with Red and Black wires, Red will be S1, Black will be S2. For CTs with Black and White Cables (most commonly small mV split core CTs) white will be S1 and Black will be S2.

Terminal Connections

Screw Clamp Type

For the best electrical connection use a ring or spade type crimp terminal, made onto the connection wire following the manufactures instructions.

  • Loosen the terminal screw, the wire clamp is retained and should move with the screw
  • Seat the terminal end or the bare wire under the wire clamp
  • Tighten the terminal screw, do not exceed a torque of 9Nm

 

Use properly terminated cables wherever possible

Post and Nut Type

For the best electrical connection use a ring or spade type crimp terminal, made onto the connection wire following the manufactures instructions.

  • Loosen the top M6 nut using a 10mm wrench
  • Seat the terminal end or bare wire in between the two washers
  • Tighten the top M6 Nut using a 10mm wrench, do not exceed a toque of 1.6Nm, be sure to provide adequate counter torque to the lower nut

Be aware the bottom nut secures the post onto the CT, it is not used to make an electrical connection

Note: Some CTs have M4 posts in this case please do not exceed a tightening torque of 1Nm

Tag Type

For the best electrical connection use a ring type crimp terminal, made onto the connection wire following the manufactures instructions.

The connection is intended to be used with a connection terminal and securing bolt (Max ¼”) by others, please follow the manufacturer’s instructions for the chosen connection method.

Wire Connections

Some Hobut CT are supplied with flying lead wire connections. These are intended for direct connection to a suitable terminal block, terminate in a suitable terminal to maintain a good electrical connection.

Mounting

BUS BAR Mounting Screws

Used on moulded case CTs – 14, 16, 17, 18, 19, 20, 21, 65, 84, 101, 105, 127, Series

For mounting to rectangular section bus bars

  1. Using the supplied fixing kit.
  2. Insert the square nut into the mounting hole on the side of the CT, insert the supplied screw into the mounting hole and screw into the nut.
  3. Secure the CT using the mounting screw

Mounting FEET

Push in type used on moulded case CTs – 13, 14, 16, 17, 18, 19, 20, Series

For mounting CT to base plane or cabinet

  1. Using the supplied fixing kit, select the mounting feet
  2. Push the mounting feet into the holes on the bottom edge of the CT
  3. Use a suitably sized fixing (max 6mm) with a washer

Plate Mounting used on Ring Type CTs – Optional Item, must be specified on order

For mounting CT to base plane or cabinet

  1. Use a suitably sized fixing (max 6mm) with a washer

 

DIN Mounting

Snap on Din Rail Mounting plate for use with moulded case CTs – 13, 14, 16

Each series of CT is supplied with its own DIN mounting clip (where available), they are not interchangeable

  • Fix the DIN mounting clip to the CT using the fixing holes on the bottom of the CT
  • Hook the fixed edge of the mounting clip over the DIN rail
  • Push the CT down so that the Spring loaded catch on the DIN rail mounting clip fully engages

Removal

  • Use a flat bladed screwdriver to release the spring loaded catch and lift the CT away from the DIN Rail.

 

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