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problem with 48vdc motor destroys relay

mrNobody

Jul 1, 2023
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hej
I working on a 48vdc motor but every time I turn it off with a relay ,the relay gets destroys.
I've tried but a flyback diode but haven't worked.
it's a pretty big motor, 1000W 48vdc 20A the relay is a 40A,
what is it I don't understand or I overlook.
Uden titel.pnghope there is someone who can and will help is really stuck

excuse my english it is not my mother tongue
 

Martaine2005

May 12, 2015
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Hello MrNobody,
Try putting the diode across the relay coil.

Martin
 

Minder

Apr 24, 2015
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The contact current rating for DC is Much lower than AC.
Is it rated 40A DC?
 

Minder

Apr 24, 2015
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Also that appears to be a DIP relay, I don't know of one at all that would be capable of switching 40A DC !!
You would need to use it to switch one capable of that DC current.
 

bertus

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Nov 8, 2019
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Hello,

Without the datasheet of the used relay, it is impossible to say what is happening.
Wich type of relay are you using and how it it driven?

Bertus
 

Minder

Apr 24, 2015
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Hello,

Without the datasheet of the used relay, it is impossible to say what is happening.
Wich type of relay are you using and how it it driven?

Bertus
The part No. has DIP for the first letters and the pinout shown also jive with DIP relay.

1688225510191.png
 
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bertus

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Hello,

@Minder , Perhaps the schematic is only to show the connection and not the actual relays.
We will have to wait for an answer on the actual used relais part number.

Bertus
 

Minder

Apr 24, 2015
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Hello,

@Minder , Perhaps the schematic is only to show the connection and not the actual relays.
We will have to wait for an answer on the actual used relais part number.

Bertus
The part No is shown, In part, alongside the relay ?
First three letters are DIP.
 

Minder

Apr 24, 2015
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Also by the part No. if it IS a 12vdc coil, then a automotive style may do the job better.
 

mrNobody

Jul 1, 2023
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So thankful for all the comments and I'm sorry for not being exact in my drawing, I'm sorry but it's only to show the connection, I don't hav access to the part no. But I sure it's a 40 amp DC relay it's controlt by a 24 vdc and one siemens logo plc, I have also tried a big 150 amp start rely, I know it will get hot but I think it's getting a little to hot, it's alle driven by to 24vdc 100Ah lithium batteries in series and I'm sorry but I can get the part numbers the day after tomorrow for all of it but if I go with the big rely can the batteries not get damage? And again thank you all
 

mrNobody

Jul 1, 2023
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Is it the relay coil that fails or the relay contacts?
It's the relay contacts as son it's it drives find at start and on but as son is I turn it off it gets the contacts to stik together and then wil not turn of again or it will get so hot that it melts it's connection to the contacts side thanks for replying
 

mrNobody

Jul 1, 2023
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Also by the part No. if it IS a 12vdc coil, then a automotive style may do the job better.
So thankful for all the comments and I'm sorry for not being exact in my drawing, I'm sorry but it's only to show the connection, I don't hav access to the part no. But I sure it's a 40 amp DC relay it's controlt by a 24 vdc and one siemens logo plc, I have also tried a big 150 amp start rely, I know it will get hot but I think it's getting a little to hot, it's alle driven by to 24vdc 100Ah lithium batteries in series and I'm sorry but I can get the part numbers the day after tomorrow for all of it but if I go with the big rely can the batteries not get damage? And again thank you all
 

Minder

Apr 24, 2015
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The size of the relay contacts are not going to affect the load.
If it is the coil gets hot and destructs, then I would suspect it has an AC rating instead of DC?
Send the part No.! If you don't have it, then how do you know the specs??
Please confirm whether it is the contacts or coil that is destroyed!!
 

mrNobody

Jul 1, 2023
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The size of the relay contacts are not going to affect the load.
If it is the coil gets hot and destructs, then I would suspect it has an AC rating instead of DC?
Send the part No.! If you don't have it, then how do you know the specs??
Please confirm whether it is the contacts or coil that is destroyed!!
I don't hav it on me at this moment but I have used them to control a inverter 48dc-220ac and got 25 amp 48vdc through them no problem and with the motor it's starts og go on now problem it's first when I open the relay it will get the contacts to stik and will then not turn off again
 

Minder

Apr 24, 2015
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hej
I working on a 48vdc motor but every time I turn it off with a relay ,the relay gets destroys.
I've tried but a flyback diode but haven't worked.
So in fact it could be welded at switch on due to high inrush current, and you would not know until you turn it off. ;)
Is this an open frame relay, or enclosed?
On this type of application, usually arc quench type relay is used on the contacts, a strong magnet is one method used
 

mrNobody

Jul 1, 2023
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So in fact it could be welded at switch on due to high inrush current, and you would not know until you turn it off. ;)
Yeah you right, but tow of them started melting at the connection to the contact side at the moment I turned it of, I'm sorry it's my first time asking on a forum, I'm very thankful for the help

Part nr. VS-T40HFL100S05

Link rs components:


It's no the correct on but similar I can't find the correct one befor the day after tomorrow
 
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Minder

Apr 24, 2015
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You may want to start looking at a SSR type circuit, using a BJT etc.
 

Delta Prime

Jul 29, 2020
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This is just an example!this is the one my friend purchased for his e-bike which is a 2000 Watt DC motor
The coil can come in different voltages and as stated by
Mr. @Martaine2005 you need an external diode for Reverse EMF. Protection!
Screenshot_2023-03-17-01-33-26.png
All the above is just an example of how you would connect you can configure it any way you wish it'll work just the same. Gives us wiring diagram of how you have everything connected or would like to have it connected.
This wire colored diagram one shows a 12 relay but what it doesn't show it's connected to the same 12 volt source along with the switch on the relay coil and I would put fuses in there on the positive rail. it depends on your skill set! But I'm pretty sure we are all more happy to help you.
Screenshot_2023-03-17-22-51-48.png
And another thing people are probably going to give you crap cuz it says China right on your relay. They used to say same thing about U.S. products right after world war II. Cheap and unreliable. Just buy from a known good vendor. But I'm glad we're not speaking German or Japanese in the U.S.A.
Happy 4th of July everyone! You want some...Get Some!! Hoorah!!
 
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