Overcurrent protection turns a protective circuit breaker or fuse into a trip point. A tripping circuit breaker or fuse closes to trip the circuit because the load current has exceeded the circuit breaker or fuse's maximum rating. If the overload protection is a thyristor, it remains in an on state but conducts little or no current. The power distribution panel can be replaced or modified to divert overcurrent to one or more subpanels that are equipped with fast-acting protection circuits.
Sure you can use a series meter to measure current, but why? It is much faster to use a shunt or clamp meter, which you will need anyway. A clamp meter is an adjustable current transformer. It consists of a shunt wound by wire with an adjustable ferrite core. It is made for measuring short-term or transient overcurrents up to some maximum, designed either by the manufacturer (T&D) or the user (Chapter 7). It is not suitable for measuring overloads or for measuring steady-state currents.
A switchoff is the act of a CT or clamp circuit breaker tripping. When a circuit breaker or fuse is tripped, we term the circuit "open"; a clamp current transformer (termed a power transformer for short) simply provides an overload on the circuit breaker. The power transformer relieves the circuit breaker or fuse and cuts off the supply to the panel. A tripped power transformer clamps the overload current to a holding current, then triggers an internal circuit breaker to free the power to the load.
There are two types of CTs, depending on the location of the secondary winding inside the core. I. The internal winding is in the core and provides overload protection; I. The secondary winding is outside the core and provides clamp current protection. CTs are often recognized by the symbols on the core, which are generally fixed by the manufacturer. d2c66b5586