Page 941 - Basic Electrical Engineering

of relays. Relays detect the fault and initiate tripping of the circuit breaker.
Under fault conditions the electrical quantities like current, voltage, and
frequency become abnormal and is sensed by the relay. There are various

types of relays, like distance or impedance relay, induction-type over-current
relay, differential relay, etc.

13.10.1 Safety Precautions in Using Electricity

Electricity has to be used very carefully. Careless use may lead to severe
consequences to the person using electricity or to the system. Every circuit

should be given supply through a switch–fire arrangement. The phase
provided should be of the proper rating. No connection should be taken

directly using naked wires. All metallic parts of electrical equipment should
be earthed.

13.11 EFFICIENT USE OF ELECTRICITY

Electrical energy is used in almost every place like in running electric trains
and metro-rails, heating and cooling of buildings, creating cold storage

facilities, illuminating building interiors, street lighting, etc. The demand for
electricity is increasing day by day. Non-renewable energy resources like

coal and gas are getting depleted. It is therefore important that we save
electricity by reducing losses and misuse.
Energy efficient technologies, gadgets, and appliances are to be developed

and the less efficient ones be replaced. For example, gradually, electric
filament lamps will be replaced by CFLs (compact fluorescent lamps).

Electronic fan regulators have already replaced the traditional variable-
resistance-type regulators. For saving energy on heating and cooling, the

losses due to leakage have to be reduced. Further, through proper automatic
control devices, constant temperature could be maintained irrespective of

variation of outside temperature. This will ensure that over cooling and over
heating is not done. The persons using electricity need to be made aware of
the need for efficient use of electricity.