Make Before Break Relay Contacts

Switch and relay contacts are usually made of springy metals.

Make before break relay contacts.

Make before break mbb is a term denoting a switch or other device in which a new electrical connection is made before the existing one is broken. Make break relay high power no contacts 12v 70a 3 8 22 more info make break mini relay high power no contacts 12v 70a with resistor 1. Relays with mbb contacts have an overlapping mechanism where the no contacts close before the nc contacts open. Multiposition switches can be either break before make most common or make before break.

In short it simply means shorting the circuit before disconnecting it. That is the no and nc contacts are never simultaneously closed during the transition between states this is not always the case form c contacts follow this rule while the otherwise equivalent form. In general relays are break before make since they work by a single leaf moving between two contacts. Switch contacts is as follows.

In most cases the rule is break before make or b b m. You should use these contacts only when your logic requires it for example to avoid a relay race or to make sure you don t have two counter acting devices on at the same time. A late break contact has the operator rigged so the nc contacts won t open until after the no contacts have closed and normal nc contacts are opened. To get a make before break you effectively have to have two completely separate contact systems which operate at different times.

These are also called continuous contacs. It sounds as though you are looking for a relay with centre off contacts like an on off on three position toggle switch. The poles of a switch refers to the number of moving contacts while the throws of a switch refers to the number of stationary contacts per moving contact. When the contacts strike together their momentum and elasticity act together to cause them to bounce apart one or more times before making steady contact.

If these exist they are very rare as most relays have only two states on off. Where a switch contains both normally open no and normally closed nc contacts the order in which they make and break may be significant. You may know about mbb when purchasing a relay. The generic symbology for n o.

The result is a rapidly pulsed electric current instead of a clean transition from zero to full current.