Loading Transformer Working Principle:
Loading transformers are nothing but a normal transformer which is designed (to operate on short time kA Loads) to inject current, to the electrical circuits such as CTs, OLR, transformers, protective relays circuit and current carrying apparatus (Busbar, cables) with various input voltage level. The input voltage will be around 110/230 volts 50/60Hz Raw power supply and the output voltage will be 5V or 10 V with high output current such as 500A to 1000A, according to the design of the transformer. Example: A loading transformer rating will be around 5 KVA. It can be used for as 5V, 1000A (parallel connection) and 10V, 500A as series connection. However, the output of the loading transformer can be increased for short time 10V 500A to 10V 750A for 30 secs as well.
Purpose of Loading Transformer:
- Fuse links
- Meter sockets
- Fuse boxes
- Overcurrent relays
- Thermal Overload relays
- Motor starter overload relays
- Oil circuit breakers
- Transformer breakers
- Disconnect switch contacts
- Instrument current transformers
- Air circuit breakers (thermal, magnetic, and thermal-magnetic
The above equipment can be calibrated using this transformer.
Image source: http://www.tesco-advent.com