thermal overload relay current setting

[YIGO]

All,
Please explain to me the impact of the thermal overload relay current setting range.
I have a relay with the following current settings: 85%, 100%, 115%.
If at 100% setting, the relay trip at t100, what would be the trip time at 85% by just adjusting the current dial.
Likewise, what would be the trip time at 115% by just adjusting the current dial.
How can this be illustrated in the TCC?.

Thanks

Yigo

 

[jraef]

What that dial is setting is the pick-up point of the TCC, the shape of the curve stays the same.

So at 85%, if you have the heaters selected for for 100A, the trip curve starts at 85A, if you set the dial to 115%, the trip curve starts at 115A.

You cannot calculate the trip time without knowing the trip class.

"Will work for (the memory of) salami"

 

[YIGO]

Jraef,
To make sure I understand you, please let me state the issue in a different way.
I have TCC curves defined as time = f(I/I-trip).
During a test,the OL relay is set at 100%, the relay trips for a current named I-100.
Using TCC curves, the time is the point where TCC intersects the current line at
(I-100/I-trip).
During a second test, the OL relay is set at 85%, the relay trips for a current named I-85.
Using TCC curve to find the time, I want to know if the time is the point where TCC intersects the current
line at (I-85/I-trip), or (I-85 x 0.85/I-trip), or (I-85 / 0.85/I-trip),

Your comments are very appreciated

Thanks

Yigo

 

[LionelHutz]

Set the overload to 100% and apply a current of X amps to the overload. It will trip in Y seconds. Now, set the overload to 85% and apply a current of 85% x X amps. It will again trip in Y seconds.

 

[YIGO]

Thank you for your responses.
You are all saying the same thing.
Moving the pick up 15% to the left or right would cause the curve
to shift to the left or right.
From my previous post, the right current is (I-85 x 0.85/I-trip).
Thanks again.

Yigo