What are the pins on a 4 pin relay?

4 pin relays use 2 pins (85 & 86) to control the coil and 2 pins (30 & 87) which switch power on a single circuit. There are 2 types of 4 pin relay available; normally open or normally closed. A normally open relay will switch power ON for a circuit when the coil is activated.

What is the 87a on a relay?

Numbers of a Relay Note that each pin is numbered. 85 and 86 are the coil pins while 30, 87, and 87a are the switch pins. 87 and 87a are the two contacts to which 30 will connect. If the coil is not activated, 30 will always be connected to 87a. Think of this as the relay in the Normally Closed (OFF) position.

What are the 4 parts of a relay?

Basic parts and functions of electromechanical relays include:

  • Frame: Heavy-duty frame that contains and supports the parts of the relay.
  • Coil: Wire is wound around a metal core.
  • Armature: A relays moving part.
  • Contacts: The conducting part of the switch that makes (closes) or breaks (opens) a circuit.

Which pin is ground on a relay?

85
Realizing that 85 and 86 are the coil pins, these pins will be transferring the current through the coil. 85 will be used to ground your relay, while 86 will be connected to the switchable power. 87 and 87a will be connected to your controlled accessories that you wish to turn on and off with your relay.

What is NC and NO in relay?

NC means normally-closed contact. NO means normally-open contact. When the relay coil is de-energized, NC contact becomes open, and NO contact closes.

What is 87B on a relay?

The Type 87B relay is a high-speed or instantaneous differential voltage device intended primarily for bus differential protection. High current sensitivity also allows the relay to be used for differential protection of resistance grounded systems and machines or reactors.

What is NO and NC in relay?

Why do buttons have 4 pins?

Most tact buttons have four pins for stability and ease of circuit board design. With four pins, you have inbuild links to skip over circuit board tracks. A 4-pin tact switch is electrically the same as a 2-pin one.