If by mistake, secondary is open circuited. The voltage across the secondary rises to very high level. The process results in zero secondary current, hence reduced back E.M.F. The working flux F increase and core gets saturated the secondary E.M.F. Increase due to increased flux some problems rises from the open circuit of current transformer is:
- The primary winding and the core are over heated. This heat may be sufficient to damage the current transformer.
- High voltage induced between secondary terminals of current transformer is very dangers on the persons and the
relays connected with it.
Note:
Dangerous of open circuit depends on some factors, load current at which the current transformer is opened, and the material of core and winding.