Relay DC rating at different voltage

[xj25]

Hi everybody,

I have an equipment with an integrated output relay with the following characteristics (from eq. datahseet, i could not know relay datasheet):
5A 30Vdc resistive load
5A 230Vac resistive load

I need it for a custom application to switch 90Vdc, load <20mA (high impedance digital input)

I use >100 of these and don´t want to use an additional DC relay from 24V to 100V for that small load.
¿what do you think? ¿any similar experience?

Regards and thanks for the replies,

 

[DRWeig]

Can you give us the manufacturer and model number for the relay that you have?

1) If your product that contains the relay is UL or otherwise listed in your area (I sense that you're not in the US), you can't exceed the voltage or the current rating.

2) If the relay itself has a listing or approval, you'll be violating it by applying voltage above the rating.

3) Switching only 20 mA is problematic unless your relay contacts are gold plated. It's best to keep the load through relay contacts above 100 mA, or 50 mA at the lowest if not gold plated. 20 mA won't allow self-cleaning of the contacts to happen and your contacts will soon become an open circuit as nasty stuff collects on them.

4) Can you use a solid state relay?

Best to you,

Goober Dave

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[MikeHalloran]

You propose to use the equipment outside of its specified envelope, so you will get no warranty from the manufacturer.

Especially if you are offering a warranty on what you are doing, you need to add a relay or a transistor or an optoisolator or something.



Mike Halloran
Pembroke Pines, FL, USA

 

[jraef]

DC switching is more difficult than AC switching, hence the lower voltage ratings on a switch if used in DC circuits compared to AC voltage ratings.
Chances are great that if used at 3X its rated voltage, the contacts will burn, or worse, weld.


"Will work for salami"

 

[waross]

I had to repair a DC relay that was used above its voltage rating. The contacts did not clear the arc and became tiny silver-alloy hourglasses.


Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[xj25]

I have not the relay model (I am trying to get a sample of the equipment to check it)
I am in old europe

Low current could be a problem for switching for some kind of relays (we have experienced some issues with that before), but expected nº of maneuvers are very low (it is a kind of trip signal, so maybe just some tenths per year), so maybe it is not a problem here. Anyway, if I change to an additional auxiliary relay will have that issue also (unless a solid state relay is used, as DRWeig proposes).

So I get general opinion that better not to risk it
it is not possible to get the "equivalent" switching rating for 90Vdc, but the power switched is so low that I will try to get a sample to do a test, and come back if positive results are shown.

Thanks for the replies!