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"What is Early Make and Late Brake Switch?"

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mmirizzi - (3 posts)	Feb-08-01, 01:02 PM (EST)
"What is Early Make and Late Brake Switch?"
Trying to understand what Early Make and Late Brake mean for a switch contact? How is each of those different from a simple NO or NC switch? Which type is better for use in an emergency stop button scenario? Please help me? Thanks Mike.
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RE: What is Early Make and Late Bra..., Tom Jenkins, Feb-08-01, (1) RE: What is Early Make and Late Bra..., kevinhammond, Feb-09-01, (2) RE: What is Early Make and Late Bra..., Terry Woods, Feb-09-01, (3)

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Tom Jenkins - (768 posts)	Feb-08-01, 01:29 PM (EST)
1. "RE: What is Early Make and Late Brake Switch?"
In a normal pushbutton or selector switch the contact blocks all operate simultaneously. Because of deadband (hysterisis) in the mechanical operation of the contacts, when you push the button the NC contacts will open first, then after a fraction of an inch additional travel the NO contacts will close. An early make contact has the operator rigged so the NO contacts will close BEFORE the NC contacts open or the normal NO contacts close. 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. 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.
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kevinhammond - (20 posts)	Feb-09-01, 07:38 AM (EST)
2. "RE: What is Early Make and Late Brake Switch?"
This has nothing to do with E-Stops, but I've used early make contacts along with standard NO contacts to get two speed control on crane hoists and other machines. Push the button in half way to pick up the early make contact and get half speed. Push the button all the way in to close the standard NO contact and get full speed. Works great! Kevin
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	Terry Woods - (708 posts)	Feb-09-01, 08:31 PM (EST)
	3. "RE: What is Early Make and Late Brake Switch?"
	LAST EDITED ON Feb-09-01 AT 09:19 PM (EST) The basic logic there is, If NOT A AND NOT B then STOP If A AND NOT B then SLOW If A AND B then MEDIUM IF NOT A AND B then FAST Trying to understand what Early Make and Late Brake mean for a switch contact? How is each of those different from a simple NO or NC switch? Which type is better for use in an emergency stop button scenario? In terms of an Emergency Stop, there is no benefit to using a "Make-before-Break" type set of contacts. When you SLAM an E-Stop that has a "Make-before-Break", the time difference between the MAKE set making and the BREAK set breaking is insignificant! There is no advantage to using this type of contact set in an E-Stop!!! The normal type of contact to use is a Normally Closed type contact. Then when you SLAM the E-Stop Push Button the contact opens cutting power to the connected devices.
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