Relay basics
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This document discusses relays, including their construction, symbol, types, and advantages. A relay is an electromagnetic switch that uses a small electric current to turn on or off a larger current. It has a coil that becomes a magnet when powered, and uses this magnetism to switch contacts like normally open (NO) and normally closed (NC). Relays have multiple poles and throws to control connections. They allow low-power control of high-power loads, and are used in applications like motor control. Relays provide advantages like low control power requirements and switching of larger loads.
Relay basics
- 1. Relays Prepared by Atheena Pandian
- 2. PRSENTATION OVERVIEW POINTS FOR DISCUSSION What is Relay? Electronic symbol Pole and Throw Construvtion Simple Circuit Diagram Types Advantages 1. 2. 3. 4. 5. 6. 7.
- 3. WHAT IS RELAY? A relay is an electromagnetic switch operated by a relatively small electric current that can turn on or off a much larger electric current. The heart of a relay is an electromagnet (a coil of wire that becomes a temporary magnet when electricity flows through it).
- 4. Symbol A single pole switch is often denoted by the letters SP, and a double pole by DP. Relays can have one, two or more poles. Common Normally Normally closed open
- 5. Throw and Pole The pole of a relay is the terminal common to every path. Each position where the pole can connect is called a throw. Throw: The number of throws on an electrical switch is the number of positions that are available. For an electromechanical relay, there are normally only one or two throws.
- 6. CONSTRUCTON Relay basically has a coil, to be specific switching coil which switches between contacts of relays It has two or more than two contacts, we will consider relay with two contacts of which one is NO (Normally open) while other is NC(Normally Closed). And a contact termed as COM (Common).
- 7. WORKING PRINCIPLE It works on the principle of an electromagnetic attraction. When the circuit of the relay senses the fault current, it energises the electromagnetic field which produces the temporary magnetic field. This magnetic field moves the relay armature for opening or closing the connections.
- 8. Simple relay switch diagram
- 9. T Y P E S
- 10. The advantage of relays is that it takes a relatively small amount of power to operate the relay coil, but the relay itself can be used to control motors, heaters, lamps or AC circuits which themselves can draw a lot more electrical power. Applications
- 11. Thank You