Connection diagram, Working Principle, Technical Parameters and Types.

  1. Full form of HT CT
  2. What is the HT CT
  3. CT connection diagram
  4. Working principle
  5. Technical parameters
  6. Types of CT

1 - Full form of HT 11/33 KV CT:

HT: High Tension - 11 KV or 33 KV power supply .
CT: Current Transformer - It is used for current or load measuring for utilisaion unit.

2 - What is the HT CT and types :

A Current Transformer (CT) is an instrument transformer. It is used for providing a current in the secondary winding. This secondary current is proportional to the primary alternating current which is passing in the primary. Secondary winding current is as low current as 1-5 ampere with the same ratio in the primary.

This current is used in metering and protective relay. Different type of CT is used in the electrical system as capacity and voltage of HT CT and LT CT.

Types of CT

According to application and range of voltage, the CT can be classified into different types:

  • HT CT. It is designed as per voltage.

    • Indoor Type: Indoor type CT is used in HT panels inside substations or industries which is used in 11 KV or 33 KV high voltage. It is made of an epoxy cast resin material. It is known as a dry type Current Transformer.

    • HT current transformer(CT) : indoor types diagram and
            working principle.
    • Outdoor Type: it is used in a substation open above area 33 KV for transmission and distribution.

    • HT current transformer(CT) : outdoor types, diagram and working principle.

3 - HT current transformer(CT) : Connection diagram.

HT current transformer(CT) : wiring, connection diagram and working principle.

4 - Working Principle:

The Current Transformer and Power transformer both are the same working. Same as the power transformer, CT has two winding primary and secondary. Primary is used for input supply and secondary is used for output supply.

Whenever the primary winding is connected to the input supply then induced emf produces in the secondary winding. When we check the load impedance in 2ndary winding is very low. The CT is operated as a short circuit secondary so it depends on flowing primary current, not in a load impedance.

CT ratio is calculated according to ratio if the primary winding is 100 amp then the secondary ratio will be one amp to five amp. We can divide 100 into 5.
1A =20 A, 2A =40 A, 3A =60, 4A =80 A, 5A =100 A.

Note: -CT secondary should not be open because CT primary depends on load, not in CT secondary. It will be open.

5 - Technical Parameters of CT:

Sr.No. Parameters Value
1 Voltage ratings: 11 KV to 36 kV
2 Insulation Rating (kV) Up to 36/70/170 KV
3 CT Accuracy Ratings .1,.2,.5, 1, 3, 5
4 Secondary Current Rating (A) 1A or 5A
5 Current Rating of Primary (A) Up to 3000A
6 Type of CT Primary Wound Type
7 Rated Burden (VA) Up to 30VA

Go back to index ↑

Electrical and Mechanical Job Interview Training.
Get boost in your job or get new opportunity

Technical e book is used for storing data in soft formate which may be pdf, ms word or others as availability.

Electrical E-book

(Get important knowledge about industrial electrical, building maintenance in E-book )

HT system, LT system, Transformer, Electrical panel, Motor and Starter, Circuit breakers, Protection relays, Measuring meters.

Interview is a physical verbal communication activity which is performed between job seekers and employers so that skilled person could be selected.

Technical Interview

( Electrical system, Diesel generator, BMS, AC, Chiller plant,
UPS, WTP, STP, ETP, Fire and safety.)

electrician, maintenance supervisor, AC operator, chiller plant operator, DG operator, BMS operator, Shift engineer, Maintenance engineer, technical executive, sr. engineer, assistant facility manager,


Learn Fast and Improve Your Skill in Electrical Field Basic and practical theory, repair and maintenance, protection and testing.

For any query :- write to us as below mentioned email ..

For official :-

For technical information :-

For interview preparation :-
Subscribe for Get Latest Post Updates in Your Email Inbox
Join Free Email Service