Tek-Tips is the largest IT community on the Internet today!
Members share and learn making Tek-Tips Forums the best source of peer-reviewed technical information on the Internet!
-
Congratulations MintJulep on being selected by the Eng-Tips community for having the most helpful posts in the forums last week. Way to Go!
Thermal Overload Relay Testing 1
- Thread starter mellomain
- Start date
- Moderator
- #2
It depends.
What are you testing for?
Note that the size of the conductors may affect the calibration. Conductors should be sized based on 75 deg. insulation.
If you test individually the relay should trip early due to differential action. If you test in series you may not identify a late tripping pole.
A complete test would include testing with rated current through two poles and a variable current through the pole under test as well as a test with the same current through all three poles in series. This way you will be able to test both differential action and overload tripping.
However, if you have a nuisance tripping issues, a first, fast test would be all three poles in series at rated current.
Bill
--------------------
"Why not the best?"
Jimmy Carter
What are you testing for?
Note that the size of the conductors may affect the calibration. Conductors should be sized based on 75 deg. insulation.
If you test individually the relay should trip early due to differential action. If you test in series you may not identify a late tripping pole.
A complete test would include testing with rated current through two poles and a variable current through the pole under test as well as a test with the same current through all three poles in series. This way you will be able to test both differential action and overload tripping.
However, if you have a nuisance tripping issues, a first, fast test would be all three poles in series at rated current.
Bill
--------------------
"Why not the best?"
Jimmy Carter
- Thread starter
- #3
I am conducting periodic testing (5 year frequency) to verify that the relay will trip within the time specified on its characteristic curve. I test at 300% of the current setting for example. The curve does not state whether or not it was developed for a single pole.
Man is troubled by what might be called the Dog Wish, a strange and involved compulsion to be as happy and carefree as a dog --- James Thurber
Man is troubled by what might be called the Dog Wish, a strange and involved compulsion to be as happy and carefree as a dog --- James Thurber
-
1
- Moderator
- #4
Test with three poles in series. Doing this test on individual poles will probably result in cross issues with the differential action.
Use the same size conductors for the test connections as are used in service. The conductor acts as a heat sink and a different size conductor may bias the results. Probably not much at 300% but using the same size wire removes all doubt.
Bill
--------------------
"Why not the best?"
Jimmy Carter
Use the same size conductors for the test connections as are used in service. The conductor acts as a heat sink and a different size conductor may bias the results. Probably not much at 300% but using the same size wire removes all doubt.
Bill
--------------------
"Why not the best?"
Jimmy Carter
- Thread starter
- #6
- Thread starter
- #7
jraef,
what I meant was that 24 to 209 is acceptable. Anything outside of that is unacceptable and requires further investigation. Could be a test method problem or could be a component issue.
Man is troubled by what might be called the Dog Wish, a strange and involved compulsion to be as happy and carefree as a dog --- James Thurber
what I meant was that 24 to 209 is acceptable. Anything outside of that is unacceptable and requires further investigation. Could be a test method problem or could be a component issue.
Man is troubled by what might be called the Dog Wish, a strange and involved compulsion to be as happy and carefree as a dog --- James Thurber
- Status
Similar threads
- Question
- Locked
- Question
- Locked
- Question