Can Thermal Overload Relay protect DC circuit ?

Thread Starter

meowsoft

Joined Feb 27, 2021
367
Can Thermal Overload Relay in Contactor, that contact DC current, can protect DC circuit from overload ?
I use schneider LC1D115M7 with thermal overload relay can protect DC circuit and wire from overload ?
*200a max capacity for AC-1, 115a max capacity for AC-3, 200a max capacity for DC-1 to DC-5 at 48-75v DC, with now, 32a 48v load, further expansion is 63a 48v, I want to add 32a thermal overload relay
 

LowQCab

Joined Nov 6, 2012
588
Please do not ask me.

This is NOT a class-room, and there are no qualified instructors here.

As far as I know, I'm the only person here who is experienced in what you are attempting.
And I will not help you,
now that I am aware of some of the crazy things that you have been asking about.

GET A PROFESSIONAL ELECTRICAL CONTRACTOR TO HELP YOU.

Don't be foolish, you may wind-up instantly DEAD.
.
.
.
 

DickCappels

Joined Aug 21, 2008
7,449
It depends on whether the contactor works well with DC. As Ian0 suggested, contact Shneider for advice. If they say it is not rated for DC then don't use it.
 

andrewmm

Joined Feb 25, 2011
1,496
Can Thermal Overload Relay in Contactor, that contact DC current, can protect DC circuit from overload ?
I use schneider LC1D115M7 with thermal overload relay can protect DC circuit and wire from overload ?
*200a max capacity for AC-1, 115a max capacity for AC-3, 200a max capacity for DC-1 to DC-5 at 48-75v DC, with now, 32a 48v load, further expansion is 63a 48v, I want to add 32a thermal overload relay
Just to note:
The reason we are worried about is it DC or AC, is a contactor behaves very differently with the two.

At the very least, spark erosion is a problem,
AC, voltage going through zero twice every cycle, the current flowing which drives the spark when contacts break is going to self extinguish very quickly.
DC, there is always a voltage, so when the contacts break open, the spark is constant till the contacts are far enough away .
If its an AC contactor , the voltage / current the contacts can take DC is much lower than with AC.
The spark is bad if long, as it heats up the contacts, if your lucky, making them black , none conductive, if your un lucky , heating them up so they fuse together closed , ..
 

Thread Starter

meowsoft

Joined Feb 27, 2021
367
It depends on whether the contactor works well with DC. As Ian0 suggested, contact Shneider for advice. If they say it is not rated for DC then don't use it.
I was contacted schneider, but they staff still don't know for thermal overload relay, contactor itself is very fine
 

Thread Starter

meowsoft

Joined Feb 27, 2021
367
It depends on whether the contactor works well with DC. As Ian0 suggested, contact Shneider for advice. If they say it is not rated for DC then don't use it.
That contactor can handle up to 200a, It's very fine for 32a, but I wasn't know, if add thermal overload relay can add protection layer, circuit breaker is 690v rated fuse and schneider MCB with 20kA breaking capacity, also doubled with MCCB
 

Thread Starter

meowsoft

Joined Feb 27, 2021
367
I was contacted schneider, but they staff still don't know for thermal overload relay, contactor itself is very fine
It's that good idea @DickCappels ?, contactor itself have max 200a load for utilization DC-1, DC-2, DC-3, DC-4, DC-5, at 48 - 75v DC, opening and closing time for 200a @48v DC is about 22 - 46 ms
 

Thread Starter

meowsoft

Joined Feb 27, 2021
367
I don't know -you will have to take the manufacturer's advice or check your local electrical code.
What's if not specified in local code ?, manufacture advice is absolutely yes for contactor itself, but hasn't been tested yet for thermal overload relay
 

DickCappels

Joined Aug 21, 2008
7,449
Are you allowed to place a thermal overload relay in the circuit with a contactor? Have you seen this done. Sometimes things we think are a good idea have hidden hazards.
 

Thread Starter

meowsoft

Joined Feb 27, 2021
367
Are you allowed to place a thermal overload relay in the circuit with a contactor? Have you seen this done. Sometimes things we think are a good idea have hidden hazards.
Yes... Is allowed to place TOR with contactor, also allowed by Schneider with AC and DC, BUT ALLOWED AND SAFE isn't mean that TOR can add security layer, is what I say, do you think that TOR can make circuit more secure ?, answer is between ("more secure" or "not have any impact"), and why ? Also is TOR can detect thermal overload in DC efficiently ?
 

Thread Starter

meowsoft

Joined Feb 27, 2021
367
Please do not ask me.

This is NOT a class-room, and there are no qualified instructors here.

As far as I know, I'm the only person here who is experienced in what you are attempting.
And I will not help you,
now that I am aware of some of the crazy things that you have been asking about.

GET A PROFESSIONAL ELECTRICAL CONTRACTOR TO HELP YOU.

Don't be foolish, you may wind-up instantly DEAD.
.
.
.
Please help, it's for scientific purpose, burnt it isn't a problem, but I don't waste more money from that, I was previously burnt 5pcs TOR with make hi pot test, 380v rated TOR used with 2000v load, was happen is they burnt about specific time, also I will take responsibility from all result
 

kaindub

Joined Oct 28, 2019
70
It is clear you have no knowledge in this area. The answers are substantially in the posts YOU have made, and additionally there is information available on the Schneider website. I know this as Inworked for Schneider and know contactors and overload relays very well.
There is no reason for a thermal overload relay to fail on a hipot test.
As others have suggested seek professional advice (not this forum) .
Its one thing to get it wrong in extra low voltage electronic circuits, but it’s much more serious for power circuits.
 
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