make and break rating of aux. relay contact 5

[sanjay12345]

Hi all,

MOst of the aux. relay manufacturer doesn't mentioned make and break capacity of aux. relay contact.

They mention 125VDC, 10A

Is this 10A is make capacity or break capacity or continuous current carrying capacity.

I am looking for a relay with 125VDC, 3A make capacity.

Help for anyone is highly appreciated.

 

[Marmite]

It would have to be make/break. What point would there be in having a 10A continuous load through a relay if you can't make or break 10A?
Regards
Marmite

 

[cranky108]

Many auxilury relays have make and carry ratings, but finding a DC rated relay with a break capacity is difficult. You can also increase the break capacity with outside devices.

And in most applications the rating is 10,000 operations, where you can increase the contact rating if you are willing to live with fewer operations to failure.

 

[JG2828]

Cranky108 is correct.

Try the ABB MG6 relay.
Make and Carry:
30 Amps @ 575 Volts ac for one minute,12 Amps continuous
Break:
Non-inductive loads only:
30 Amps @ 115 Volts ac
20 Amps @ 230 Volts ac
15 Amps @ 460 Volts ac
10 Amps @ 575 Volts ac
30 Amps @ 12 Volts dc
15 Amps @ 24 Volts dc
10 Amps @ 32 Volts dc
8 Amps @ 48 Volts dc
3 Amps @ 125 Volts dc ***
1 Amps @ 250 Volts dc

http://www05.abb.com/global/scot/sc...a370fa944c12574ce00550e8d/$file/41-753.1N.pdf

 

[dpc]

You can increase making capacity by putting multiple contacts in parallel. Breaking capacity can be increased by putting multiple contacts in series.

David Castor

http://www.cvoes.com

 

[Laplacian]

I have searched a long time for a hermetically sealed relay capable of 5-10A DC break ratings at 135VDC for use in hazardous locations. I recently found some hydrogen filled DC contactors from Tyco and Gigavac with astronomical current and voltage ratings for their small size. We plan to install our first units in the plant in October to replace mercury displacement relays that are vibration/position sensitive. These DC contactors were designed for the aerospace industry and are vibration tolerant and not dependent on position.

 

[odlanor]

capacity contacts of binary oputput- Signalling/trip relays of Siemens mltifunction numeric relays:
Make/break capacity CLOSE 1000 W/VA
BREAK 30 VA
40 W resistive
25 W/VA at L/R ? 50 ms

 

[sanjay12345]

HI DPC,

Little bit confusion.


"making capacity by putting multiple contacts in parallel."

"Breaking capacity can be increased by putting multiple contacts in series"


Why for breaking capacity, contacts should be in seris.

As per my understanding,while breaking also you are breaking current and need contacts in parallel.


your explanation is highly appreciated.

 

[davidbeach]

You break current by creating an air gap too large for the voltage to sustain an arc across. Contacts in series multiplies the air gap length. Any number of contacts in parallel that don't produce enough air gap individually will be unable to interrupt the current.