Question

Each motor used in a continuous-duty application and rated more than one horsepower is required to be protected against overload. A separate overload device that is responsive to motor current is one of four options permitted to protect against overload.__________

Answer 1

Answer:

True

Explanation:

Every electrical installation must be provided with a series of protections that make it safe, both from the point of view of the conductors and the devices connected to them, as well as the people who have to work with it.

There are many types of protections, which can make a completely safe electrical installation against any contingency, but there are three that must be used in all types of installation: lighting, domestic, power, distribution networks, auxiliary circuits, etc., already Be it low or high voltage. These three electrical protections, which we will describe in detail below are:

a) Short circuit protection.

b) Overload protection.

c) Protection against electrocution.

We understand by overloading to the excess of intensity in a circuit, due to a fault of isolation or, to a fault or excessive demand of load of the machine connected to an electric motor.

Overloads must be protected, as they can lead to the total destruction of the insulation, a network or a motor connected to it. An unprotected overload always degenerates into a short circuit.

According to the electrotechnical regulations "If the neutral conductor has the same section as the phases, the overload protection will be done with a device that only protects the phases, on the contrary if the section of the neutral conductor is inferior to that of the phases, the protection device must also control the neutral current ". In addition, a protection must be placed for each circuit derived from another main.

The most used devices for overload protection are:

- Calibrated fuses, type gT or gF (never aM)

- Circuit breakers (PIA)

- Thermal relays

For domestic circuits, lighting and small motors, the first two are usually used, as well as for short circuits, provided that the type and calibration appropriate to the circuit to be protected is used. On the contrary for three-phase motors, the so-called thermal relays are usually used.