Make Before Break Relay Contacts

In short it simply means shorting the circuit before disconnecting it.

Make before break relay contacts. You may know about mbb when purchasing a relay. 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. Multiposition switches can be either break before make most common or make before break. Is there such a thing or a specific term for break before make relay that can delay between breaking and making connection.

Mbb contacts is an abbreviation for make before break contacts. To get a make before break you effectively have to have two completely separate contact systems which operate at different times. 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. These are also called continuous contacs.

If these exist they are very rare as most relays have only two states on off. Relays with mbb contacts have an overlapping mechanism where the no contacts close before the nc contacts open. The result is a rapidly pulsed electric current instead of a clean transition from zero to full current. 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. 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. Switch contacts is as follows. The generic symbology for n o.

It sounds as though you are looking for a relay with centre off contacts like an on off on three position toggle switch. In most cases the rule is break before make or b b m. 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. Where a switch contains both normally open no and normally closed nc contacts the order in which they make and break may be significant.

It is more normal to use two separate relays and control them at different times if you really need make before break.