What is a Make and Break Relay Switch?

Monday, 3 November 2014  | 

  This post covers the make and break switch relays covered in the range of auto electrical products at Arc Components Limited. The relays supplied in-store are configured to DIN 72552 terminal standardisation and examples can be found in the switch relays section.

  What is a make and break relay?
 The most common make and break relays are produced to switch a single feed line (usually positive) to power a section of a circuit, the relay is switched manually via a toggle/push switch or remotely through the circuit. A simple 'single line switch' is achieved by switching a line input from terminal 30 to 87 (indicated by the 'thick set' black lines on the diagrams below), that 'makes' or 'breaks' once the coil has been energised by current, activating the coil via terminals 85 and 86, which can be swapped for energising in some applications if suppression (example: diode) is not present.

  There are many configurations of a make and break relay used for automotive electrical circuit switching, each allowing a variation on the switch operation, versions include normally open (NO) or normally closed (NC) operation, fused and line suppression.
Typical builds are:

  • Single line make and break relay: as described above.
  • Fused make and break relay: internally configured between 30 and 87 for the accommodation of a replaceable fuse.
  • Make and break relays with diode: used for suppressing coil voltage spikes, 85 and 86 terminals become polarity sensitive; 86 must remain positive if the diode tracks according to the diagram example below. 
  • Make and break relay with resistor: used for a more reliable suppressing of coil voltage spikes, 85 and 86 can be swapped for coil energising in some instances as the terminals do not become polarity sensitive.
  • Double make and break relay: allowing switching of two outputs at the same time (utilising 87b as a second output line).

Relay Coil - Positive and Negative Coil Energising by DIN 72552 Definition.

Terminal or ContactIdentification
85Relay coil negative.
86Relay coil positive.

 

Relay Contacts - Line Feed or Switching by DIN 72552 Definition.

Terminal or ContactIdentification
87Common contact.
87aNormally closed contact.
87bNormally open contact.
88Common contact 2.
88aNormally closed contact 2.
88bNormally open contact 2.
30Feed or line in, positive.

 

Examples of Make and Break Relays:

Standard Make and Break (NO)Standard Make and Break (NC)Double Make and Break
Single Line, Normally Open (NO) Make and Break Relay Standard Normally Closed (NC) Make and Break RelayDouble Make and Break Relay
Make and Break with DiodeMake and Break with ResistorFused Make and Break
Make and Break Relay with DiodeMake and Break Relay with ResistorFused Make and Break Relay

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