Ice Cube Relay ratings

Status
Not open for further replies.

JGRC

Member
Location
Texas
Anyone know if relays are rated at 100 percent?
Example a 5 amp contact current listed ice cube relay. Good for 5 amps continous current or would you have to derate like a breaker to 80 percent load (4) amps?
 

kwired

Electron manager
Location
NE Nebraska
Anyone know if relays are rated at 100 percent?
Example a 5 amp contact current listed ice cube relay. Good for 5 amps continous current or would you have to derate like a breaker to 80 percent load (4) amps?
Usually rated for full 5 amps, but often they will say X amps (inductive), X amps (resistive) so type of load supplied needs consideration. Some contacts may have a tungsten filament rating as well.
 

gadfly56

Senior Member
Location
New Jersey
Occupation
Professional Engineer, Fire & Life Safety
Usually rated for full 5 amps, but often they will say X amps (inductive), X amps (resistive) so type of load supplied needs consideration. Some contacts may have a tungsten filament rating as well.

Usually they will also indicate expressly if they are continuous duty, or rated at say 50% or so.
 

don_resqcapt19

Moderator
Staff member
Location
Illinois
Occupation
retired electrician
If you are switching an inductive load look at that rating too....sometimes the break rating for an inductive load is 1/10 the make rating for that same load.
 

petersonra

Senior Member
Location
Northern illinois
Occupation
engineer
Anyone know if relays are rated at 100 percent?
Example a 5 amp contact current listed ice cube relay. Good for 5 amps continous current or would you have to derate like a breaker to 80 percent load (4) amps?

I would not derate, however, keep in mind that these type of relays are usually only suitable for pilot duty unless otherwise noted.
 

JGRC

Member
Location
Texas
The ampacity that is actually switched is a total of 1.7 amps. Three very small 1 phase 120v AC magnetic induction pumps.
My thought is if its rated at 5 amps 250v (1250 watts) and I'm switching a 120v 1.7 amp load (204) watts. Seems well within its AC listed capacity range.

Thoughts?
 

gadfly56

Senior Member
Location
New Jersey
Occupation
Professional Engineer, Fire & Life Safety
The ampacity that is actually switched is a total of 1.7 amps. Three very small 1 phase 120v AC magnetic induction pumps.
My thought is if its rated at 5 amps 250v (1250 watts) and I'm switching a 120v 1.7 amp load (204) watts. Seems well within its AC listed capacity range.

Thoughts?

At that level, I think you would be fine using that relay for this service. Assuming it isn't a worthless hunk of junk otherwise. ;)
 

don_resqcapt19

Moderator
Staff member
Location
Illinois
Occupation
retired electrician
Often the details for the ratings with an inductive load are hard to find in the specs. Do you have a part number and brand for the relay you are planning on using?
 

JGRC

Member
Location
Texas
Often the details for the ratings with an inductive load are hard to find in the specs. Do you have a part number and brand for the relay you are planning on using?

after some digging I was able to find this spec sheet. Relay is a four pole.
 

Attachments

  • Untitled.jpg
    Untitled.jpg
    30.5 KB · Views: 0

JGRC

Member
Location
Texas
@250 it wont, but what would be the 125 volt equivalent ampacity alowance?...if its 1/2 the voltage should be close to double the amps which would be right at 1.6amp just shy of my 1.7 max I'm getting.

Should be right at the rating for it.

From what i read damage to contacts will be from switching the load and its rated at 500VA. Im at 204VA.
 
Last edited:

don_resqcapt19

Moderator
Staff member
Location
Illinois
Occupation
retired electrician
@250 it wont, but what would be the 125 volt equivalent ampacity alowance?...if its 1/2 the voltage should be close to double the amps which would be right at 1.6amp just shy of my 1.7 max I'm getting.

Should be right at the rating for it.

From what i read damage to contacts will be from switching the load and its rated at 500VA. Im at 204VA.
I really don't think it works that way, but I could be wrong.
 

Jraef

Moderator, OTD
Staff member
Location
San Francisco Bay Area, CA, USA
Occupation
Electrical Engineer
For the inductive rating, that voltage is a maximum voltage, the amp rating would be the same. So it is .8A inductive because of the high starting current on an inductive load, at any AC voltage UP TO 250VAC. That then would be inclusive of 120V.

A typical"ice cube" relay with a basic 10A resistive load rating is good for 1/2HP at 120VAC. If your motors are 120V 1.7A and probably no better than a .7 power factor, you are looking at 291W, (not 204W, you forgot the PF), so .39HP or a bit over 1/3. I looked around and could not find any 5A rated relays that even had a HP rating on them but if at best it would be 1/2 of that of a 10A relay, you are looking at a 1/4HP maximum limit on that relay, probably less. I did find an 8A rated relay spec sheet that listed the HP at 120VAC as 1/4th, so I'd extrapolate about .18HP as your peak, about half of what your motor is.

That relay would likely be one and done at 1.7A inductive...
 

JGRC

Member
Location
Texas
That relay would likely be one and done at 1.7A inductive...

Manufacture says there is a calculation for voltage he would email me tomorrow.

It's not one and done. I can switch it all day long and i can only visually see an arc about one out of every three breaks of load. And when i do see it it is minimal.
 

JGRC

Member
Location
Texas
After speaking with an engineer with the manufacture he was able to shed some light on the subject and explain a few things. He directed me to these attached specs.

The .8A @ 250VAC inductive rating is based on 200,000 minimum life operations as listed/tested. Attached is an inductive (and resistive) cure of amperage relation to the life operations.

The curve shows the .8A @ 250VAC to equal (200 X 10 to the third power) or 200 X 1,000 = 200,000.
At my 1.7A inductive current it shows 100 X 1,000 = 100,000. So basically at 1.7A ill limit the listed life operations to half which explains my little to no arc. My expected 6 operations max a day will make the relay last a very long time for me.

There is also a max switching current that is also variable depending on the voltage when dealing with inductive load as 120VAC it is increased to 3A VS the 2A at 250VAC
 

Attachments

  • MY4 Curve.jpg
    MY4 Curve.jpg
    34.3 KB · Views: 0
  • MY max switch rating.jpg
    MY max switch rating.jpg
    18.6 KB · Views: 0
  • Operations.jpg
    Operations.jpg
    30.2 KB · Views: 0
Status
Not open for further replies.
Top