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Output load capacity of relay.

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innovetion

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Hello,

relay.jpg

I am using a relay of 5V. Please check image for more information. I have connected this relay with microcontroller as given in following link.
**broken link removed**
My circuit work well with AC bulb. Now I want to drive a load of more capacity. I want to calculate that what is the maximum load capacity that given relay can drive.
How can I calculate ?
 

You did not mentioned what is the current wattage of the bulb, neither the AC voltage. Anyway, in order to determine the maxumum allowed loead that this relay is able to drive, you need just to multiply the nominal voltage with the nominal amperage, like that:
  • For 220Vac: 220x7A = 1,540W
  • For 120Vac: 120x10A = 1,200W
 
I was calculating like that only but I wasn't sure.
Right now, I am using a bulb of 20W
Thanks a lot.
 

I was calculating like that only but I wasn't sure.
Right now, I am using a bulb of 20W
Thanks a lot.
Click to expand...

Hi
Instead of talking about power and how much power it can handle you'd better to focus on value of voltage and current . i know you're using a bulb and it's a negligible load for such a relay but for your information 0.2v 100 A is also 20 watts ! 200ma 100 volt is the same too ! but indeed that relay can't handle 100 A !
So you always must take care of both voltage and current that it can handle .

Best Wishes
Goldsmith
 
Motors tend to use 8x Surge current relative to rated current
Light bulbs use 10x surge current relative to rated power > current.

Thus contact derating is needed. But you can use a small relay to driver a larger Contactor Relay. with current gain of 1000 minimum.

MAX. SWITCHING CURRENT:7A, 10A
MAX. SWITCHING VOLTAGE:28V DC/ 250V AC
DIELECTRIC STRENGTH VR.M.S: BETWEEN OPEN CONTACTS =750VAC;

DC is lower due to arc quenching is not possible if current is too high.
 
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