An earth leakage circuit breaker (ELCB) is a safety device used in electrical circuits with elevated electrical impedance to prevent electrocution. Unlike a RCCB, an ELCB is operated by voltage. It notices tiny lost voltages on metal casings of electrical devices and disrupts the circuit if a hazardous voltage is spotted. So the main purpose of ELCB is to avoid harm to people as a result of electric shock.
An isolating transformer is a transformer used to transfer electrical power from a source of alternating current (AC) power to some equipment or device while isolating the powered device from the power source usually for safety reasons. Isolating transformers provide galvanic isolation and are used to protect against electric shock. They block transmission of DC component in signals from one circuit to the other but allow AC components and signals to pass.