Relay specifications

[Tantalum]

Hello

I have 3 questions about a relay.

Q1: I needed a power relay for high DC (24V, 16A max) and on mouser I found the HE-S series from Panasonic.
But it's not really clear if it is really safe to use them with DC current. In the datasheet there are some DC specs but not as detailed as for AC.
I would say it's ok for DC usage (according to the last graphic), but I prefer somebody to confirm.







Q2:
On the 3rd image, there are specs for inductive load, but only for AC current, nothing for DC current. What about the max DC current for inductive load???

Q3:
On the second image there are the contact resistance specifications.
First I find the data inaccurate 3...100mOhm. Strange not?
And what do they mean with (by voltage drop 6V DC 20A) ?


Thank you

[Vovk_Z]

Q1: A1: from Max switching capasity figure it is capable to commutate 24V DC 16A, active load.
Q2: A2: of cause it highly depends on inductivilty. The worst case the switching capability decreases in up to about ten times. So it will withstand only about 3 A of highly inductive current at 24VDC (I may wrong, but +- so).
Q3: A3: don't know that contact science but contact resistance depends (nonlinear) on commutating current value (because of arcs/sparcs etc).

[Tantalum]

Thank you very much for your answers 

Q2: A2: of cause it highly depends on inductivilty. The worst case the switching capability decreases in up to about ten times. So it will withstand only about 3 A of highly inductive current at 24VDC (I may wrong, but +- so).

Would a snubber solve the issue?


(Well actually, there won't be big engines on the circuit. Only some (solenoid) electromechanical valves)

[TimFox]

That snubber network has problems with AC, since it passes some current with the contact open, but should work for DC.
However, it is usual with inductive loads to include a diode across the inductor (reverse biased when voltage applied to the load) to catch the inductive kickback when the current is interrupted.

[Vovk_Z]

Snubber helps a lot of cause but not 100%. It can be used in parrallel with a load first, so eliminates a need to put it parallel to relay contacts. And of cause it may be two snubbers - "main" one across an inductive load and second one (with lesser/smaller capacitor) across relay contacts.
Snubber helps to increase significally relay contacts life but first relay have be capable to. I mean if relay contacts are not rated for some load then it is very hard to change it significally with a snubber. (Otherwise a snubber must be about a size of a load).