Why isolation tranformer used in mcc panel?

Isolation transformer at MCC are usually Y-Delta connected, so a fault on low voltage Y side would not travel towards high voltage delta circuit, so providing isolation to HV side

1. The provided answer is not totally accurate. Yes, an isolation transformer is used to transfer the electrical power from an AC source to some equipment or control circuit while isolating the powered device/ circuit from the power source, i.e. isolating the secondary side from the primary side, and this is for safety reasons. The isolating transformer has a dual winding, contrary to single winding transformers. An isolating transfer may be400V/230V, or230/230V, or230v/24v ect.. and not necessarily a star delta connected.