Hi, I’m somewhat of a noob when it comes to electronics. I have a 58V system in my camper, and want to use a 12V relay to switch some loads.
I purchased J115F31C12VDCS.9 based on the attribute (Switching Voltage: 277VAC, 110VDC - Max) thinking that it would work well for my application. I’ve received the relay, and now I’m questioning whether it can switch up to 58V. The writing on the relay says “(NO|NC) 30A… 14VDC.” This is much lower than the 110VDC listed in the product description. To make matters more confusing, the datasheet lists 110VDC as a coil voltage. I thought this coil voltage is what’s used to activate the coil (12V in this case), and switching voltage is the voltage which can be switched by the relay.
Is the product description incorrect? Is it displaying max value out of the datasheet (which is actually for a different SKU in the same series?) If this relay is incapable of switching 58V, which relay should be used to do so?
I spent a long time filtering/searching for the right relay and it sucks that I probably made the wrong decision, paid for shipping, etc. Thanks.
According to the data sheet the 14VDC is the TÜV Contact Rating for the NO & NC contacts.
The UL rating is 30VDC for the NC contact and there is no DCV rating for the NO contact.
Those are the TÜV & UL rating qualifications the manufacturer was willing to pay to to be tested for.
The generic manufacturers rating is 110VDC, that is the value to use if a user does not need TÜV or UL ratings.
Also notice the caveat they add to the data sheet:
Values can change due to the switching frequency, desired reliability levels, environmental conditions and in-rush load levels. It is recommended to test actual load conditions for the application. It is the user’s responsibility to determine the performance suitability for their specific application.
I would have no problem using that relay @ 58VDC for personal use, assuming the wiring is properly fused and I was willing to monitor the relay enough to catch a failure that might occur at less than the rated 100,000 cycles.
Please allow a quick follow up comment for the benefit of our readers.
The contact voltage will be very different for a DC vs an AC load. The DC rating will be considerably lower. It’s physics: an AC arc is easier to extinguish when compared to a DC arc. This is due to the fact that AC has two points of zero voltage every cycle.
On a related note, this is why you NEVER mismatch automotive and line fuses. An improper fuse could result in a sustained arc, explosion of the fuse body, and fire.
This is reflected in this snippet from the datasheet where we see a low voltage for the DC application.
Without knowing more about your application, I cannot in good conscience recommend a relay. However, your suspicions are correct. You are in certainly in the yellow and approaching, or even in the red zone, with the chosen relay.
Please let us know if can provide further assistance.
Thanks for the reply APDahlen. Yes, I understand the reason for AC/DC ratings being significantly different. I feel like I’ve learned a lot since I originally posted this question. I also found out what you posted in regards to fuses (and fuse holders.) Most “standard” ones are rated up to 32V DC. I’ve purchased some Optifuse brand fuses and holders that are compatible with 58V DC, which are perfect for my system.
My application is low amperage (0.5A-3A) switching of loads in my RV. These loads are not going to be switched often, and the majority of them are NC. I have a cheap 12V relay board (with 16 relays) and am currently switching the loads using the built in relays. I should probably find some relays that are rated at 48V and daisy chain them.
Glad we could help.
You aren’t kidding, as there is so much to learn.
Then, there is another level with the application with even more relating to safety and compliance with various regulations.
Have a good weekend and I hope to see you in the future.