I want to know if this relay will be suitable for the following application:
Coil voltage will be 12 V DC. The voltage through the contacts will be 60 V DC at 2 A. It is being used to supply power to a DC/DC step down converter.
I found this particular relay (link). But I see it says the following:
250 VAC, 125 VDC (30 VDC when UL/CSA standard is applied)
Does this mean, that this relay is actually specified for 30 VDC and not 125 VDC or can I still use this relay?
Here is a graph from your linked relay data sheet
With a Pure Resistive load, you can expect to be able to switch 500 mA at 120 VDC, or 8 A at 30 VDC (it's this difference that causes the UL/CSA caveat) and it looks like from the graph, 60 VDC and 2 A, while meeting the rated 100 k operations lifetime under load.
With other than a pure resistive load, you will need to derate. With an inductive load, contact separation will induce a high voltage that will make the contacts arc and die quickly. With a capacitive load, contact closure will induce a high current that could weld or erode the contacts and make them die quickly.
You say that you want to supply a DC-DC converter. They invariably have a filter input, which will usually be capacitive input or sometimes inductive input.
Therefore, the answer is no. 60 VDC at 2 A is right at the top limit for resistive switching, and you want to switch a filter input, which will be reactive. The relay will probably last a few switching operations, but will not meet its 100 k operations under load rating. If 'a few' is enough for your particular application, then the answer is yes.
Switching 60 V at a few amps, sounds like a job for a FET!
When DC is being switched the arcing can be really bad because the spark may take a long time to go out giving very short contact life .On AC the zero cross gives the arc some time to go out .It is normal for relays that are small and cheap and have close contacts to have DC voltage ratings that are much lower than the AC rating .It is not uncommon to see mains relays rated for only 28VDC .So be careful .Check for arcing when testing ,The transparent ones are good for this .Snubb the contacts .Double check the DC rating .
No the relay is not OK for driving a capacitive load of a DC converter input. The surge current is likely to exceed beyond 2A.
The relay contacts are rated for 2A resistive load at 60V and you don't have a resistive load.
If you switch loading without big inductiveness or capacitance, that draw 2A at 60V, than relay that can withstand 10 A at 120 VAC is suitable for you.
But if switch, for example, big DC motor, than you need more complex research, because relay mechanically disconnect two wires, and load with big inductiveness can do many bad events( such as sticking relay, burned contacts in relay and so on).
