Hi, would like to know for the Current Transformer, the auxiliary control cabinet, what is the purpose of having short-circuiting links with easy access? one side of the secondary winding of each current transformer is grounded.

Thanks.

A CT with current in the primary will develop a potentially dangerous high voltage if the secondary circuit is opened. These voltages can be life threatening and damage insulation. Therefore, it's essential that a short circuit is applied to the secondary circuits before any disconnections/ insertion of test plugs etc are done and this activity should be planned into the safe system of work for the task in hand. This process requires training/ competency and untrained persons should not attempt this.

Whilst it can be argued that if the primary circuit is disconnected, then there's no possibility of developing any voltage on the CT secondary, it is good practice to apply the short circults in any case to avoid the nasty consequence of any memory lapse.

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Jonno

There are one or two people I know who wished either themselves or others had the knowledge to apply the short circuit.

Always short down the CT's when doing any work on the the meter side, As Jonathon has stated the voltages are high and damaging to cable insulation and also to anyone who comes in contact with the open ends.

Safe system of work required and correct training needs to be in place, have seen the shorting terminals installed round the wrong way!

The CT seconadry shorting llinks are extremely useful for number of online tets carried out whic are mandatorily to be carried out ON LINE ie without isolating CT from primary circuit . The typical tests are 1) phase angle measurement in the metering and protection circuit 2) Busfault stability and 3 ) Transformer differentiial protection stability test. They are also used to isolated particular circuit from Busfault looping .