Contradiction in relay rating

[throbscottle]

I have found something peculiar.
I pulled a couple of relays of an old board, they are from the Nais DS2 series. The markings on the relays themselves give contact ratings of (I think - don't have them to hand to check) 0.5A. But the datasheet gives a carrying current of 3A.
Can anyone explain the discrepancy?

Thanks

 

[MaxHeadRoom78]

Relays have different code classifications and also contacts are rated for DC/AC, inductive/resistive loads, frequency of operation etc.
Each have very different characteristics.
Max.

 

[Mikebits]

If you don't have the relay in hand, why do you think it is .5A?

 

[Reloadron]

Relays have different code classifications and also contacts are rated for DC/AC, inductive/resistive loads, frequency of operation etc.
Each have very different characteristics.
Max.

What he said for starters.

Ron

 

[MaxHeadRoom78]

What he said for starters.

Ron

He asked for an explanation of the discrepancy?
Also called form factor.
https://media.digikey.com/pdf/other...her doc/small signal relay techincal info.pdf
The discrepancy is due to the different operating modes or usage!
Max.

 

[ronsimpson]

Some relays will also have a rating for "motors". That is different than for a restrictive load.

 

[throbscottle]

You are all missing my point!
I was mistaken about the current rating, which was from my memory, but it is still very differerent from the data sheet
The photo shows the markings on one of the relays. It is a Nais DS2Y-S-DC5V. It clearly shows 0.3A at 125VAC or 110VDC, or 1A at 30VDC.
Now if you look at the datasheet, the maximum switching current is 2A and the max carrying current is 3A. Even taking into account the switching power, of 60W or 62.5VA making the 30VDC off the case marking, this should still be 2A, or about 0.5A at the higher voltages. Also the datasheet states twice the max switching voltage to that shown on the case marking.
It's as though it's a compleley different relay.
So why would the manufacturer mark the case with one rating, and state a very different rating on the datasheet?

 

[alec_t]

Check the Expected Life figures in the datasheet. For example, the 1A @ 30VDC marking on the relay corresponds to an expected life of 5 x 10^5 operations, whereas the 2A rating is for only 1 x 10^5. Although not stated as such, there would be a difference between 'normal' current rating and absolute maximum current rating.

 

[ronsimpson]

Data sheet:
1A, 30VDC, 500000 operations.
2A, 30VDC, 100000 operations.
At 2A it lasts 1/5 as long.

 

[throbscottle]

Mmm, OK that makes sense. So the device marking corresponds to longest possible life.
So, this relay might have to carry 3A, but it should never have to switch significant current, so I'm good to go
Thanks

 

[vtech]

So why would the manufacturer mark the case with one rating, and state a very different rating on the datasheet?

Wow, what a coincidence, a couple of years ago in the process of building a Panasonic ATE, I ran in to the exact same situation with the DSxx series. Due to strict compliance & documentation issues at work, had to get to the bottom of it.
Response from Panasonic Industrial Engineering was simply due to a "marketing mistake" that crept in the datasheet!
I was told to use the stamped amperage on the relay.

 

[MaxHeadRoom78]

I was told to use the stamped amperage on the relay.

+1, That would be my choice too!
Max.

 

[throbscottle]

That's a really informative pdf btw, Max