Relay & Timer Contacts
Relay & Timer Contacts
(OP)
What is a "race" or is it "rise" of a contact?
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS Come Join Us!Are you an
Engineering professional? Join Eng-Tips Forums!
*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail. Posting GuidelinesJobs |
|
RE: Relay & Timer Contacts
The contact race is between two different contacts, each part of a different relay. The one that closes or opens first or closes first logically counts. This is normally to be avoided since it is not easy to determine which contact will close first.
The contact rise may be viewed as an approaching movement in the energized condition of relay, contactor, etc.
RE: Relay & Timer Contacts
Is this something anyone has ever experienced?
RE: Relay & Timer Contacts
Relay contact race is rare. It would indicate a lack of experience in the switching logic engineering or design.
RE: Relay & Timer Contacts
You are good, very good, all that you said is true except ...
You live in a nice situation evidently.
I see horrible stuff all the time, beyond description bad.
Backfeeds, relay races, poor connections, erratic everything. I saw one panel recently sold to a GSA project, high security, cannot even go onto the site without much advance notice.
They asked me to look at their panel, not working since new about 1 year ago. Not one stinkin feature worked as specified, in fact, no worky at all except it did turn on the pump automatically. What do they do? They work stuff by hand, never go back and demand satisfaction from the builder.
There is more junk out there than we will ever know.
In fact, I bet all the new guys do not know how much about how to build with relays, they learned on ladder logic where the PLC prevents those problems.
PUMPDESIGNER
RE: Relay & Timer Contacts
Zvi Kohavi "Switching and Finite Automata Theory," 2nd Ed., McGraw-Hill, 1978, is missing important practical coverage of contact "make-before-break" and vice-versa.