These are used in conjunction with contactors and motor control equipment. They provide accurate reliable against overload & single phasing.
SPECIAL PURPOSE TRANSFORMERS
Poly Carbonate Current Transformers
- Poly carbonate is durable material
- High Impact resistance
- Low scratch resistance
- Usable in a wider temperature range
- Compact in size compared to resin cast CT’s
- Requires less cycle time compared to resin hence faster delivery.
Relay Operated Current Transformers
Air Circuit breakers Current Transformers
Air Circuit Breakers are used right upto 6000A. For thermal & thermo magnetic protection CT is integral part. CTs are available in various insulation forms such as castings, thermoplastic & tape insulated.
CBCT
- Used for earth fault protection in grounded three phase systems
- All the three phases are made to pass through the CT inner window
Summation CT
- Consist of two or more primary windings which are connected to the feeders to be assumed.
- A single secondary winding, which feeds a current proportional to the summed primary current.
Class PX CTs
- In balance systems of protection, CT’s with a high degree of similarity in their characteristics is required. These requirements are met by class PS (PX) CT’s.
- Their performance is defined in terms of a knee-point voltage (vk). the magnetizing current (imag) at the knee point voltage or 1/2, 1/4 the knee-point voltage, and the resistance of the CT secondary winding corrected to 75~c (Rct)
Autotransformer
- In an autotransformer, portions of the same winding act as both the primary & secondary sides of the transformer.
- They are often used to step up or step down voltages in a smaller range. (eg. 110-115-120v)