Page 242 - Electrician - TT (Volume 2)

ELECTRICIAN - CITS

10 Rectifiers (Fig 15)
A rectifier is a static device consists of one or more diodes that converts alternating current (AC) to direct current
(DC). A diode is like a one -way valve that allows an electrical current to flow in only one direction.
11 Limit switches (Fig 16)
Limit switch is a switch with an actuator which is operated by the motion of a machine part or an object.
When an object or parts comes into contact with actuator, it operates the contacts of the switch to make or break
an electrical connection. They are used to control the distance or angles of movement of any machine parts or
axis or objects.

Fig 15 Fig 16

12 Control transformer

It is a transformer which is used to supply the power to the control or auxiliary circuit or equipment which does not
intend for direct connection to the main supply.
13 Panel meter (voltmeter and ammeter)
They are the measuring instruments used to measure the various electrical parameter of the circuits such as
voltage and current etc.
Wiring accessories for control panel wiring
1 PVC channel / Race ways (Fig 17)

It is an inspection type PVC enclosed channel which provides a pathway for electrical wiring inside the control
panel. It has the opening slots on both sides to facilitate the good ventilation and visual inspection.
It protects the wires from dust, humidity, corrosion, water intrusion, heat, mechanical damage and physical
threats.
2 DIN rail (Fig 18)
It is a zinc - plated or chromated metal rail which is used for mounting the control accessories like MCB, contactors
and OLR etc, with out using screws inside the control panel.

Fig 17 Fig 18

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CITS : Power - Electrician & Wireman - Lesson 93-100 CITS : Power - Electrician & Wireman - Lesson 93-100