i have this another setup where i connected a 12v 5a 3PDT Relay with a 12v 1A adapter,
am i right that from the given coil rating of the relay (12v) and a contact rating of 5Amax, the maximum wattage that it can handle would be 12v x 5a which is equal to 60W ?
what if i connected it with a 12v 1A adapter ? does this mean that the relay can now only handle 12v x 1a = 12Watts maximum contact rating ?
or it can still handle 60W regardless of the amperage of the adapter i use as long as it is 12V and not exceeding the maximum contact amperage which is 5a ?
Show us a link to the relay data sheet.
My first thought would be this has a 12 volt coil with contacts rated at 5 amps each.
You could put the contacts in parallel.
But we need to see the data sheet to see what voltage the manufacturer gives to the contacts rated at 5 amps,
This could be 12 volts at 5 amps or 120VAC at 5amps etc.
Neither of which is the maker's datasheet. The datasheet may be hidden in those two pages somewhere, but what you should really post is a link to the datasheet on the maker's site.
But that won't double the capacity since the contacts separate at slightly different
times and thus the spark damage occurs on only one set. You need a larger
relay for larger current.
Place SWC on the contacts to suppress the arcing.
Large or small contact surface they only touch in a very small area.
Paralleling the contacts does increase the current capability to handel the load.
urbanmiles:
i have this another setup where i connected a 12v 5a 3PDT Relay with a 12v 1A adapter,
am i right that from the given coil rating of the relay (12v) and a contact rating of 5Amax, the maximum wattage that it can handle would be 12v x 5a which is equal to 60W ?
what if i connected it with a 12v 1A adapter ? does this mean that the relay can now only handle 12v x 1a = 12Watts maximum contact rating ?
or it can still handle 60W regardless of the amperage of the adapter i use as long as it is 12V and not exceeding the maximum contact amperage which is 5a ?
step back a second.
a relay has 3 components.
// === COIL ==========================================
one is the coil. you cannot control the voltage, that is set. you cannot control the wattage, that is set. the information is only for your sizing of the power supply for the COIL.
// ===== signal =============================
all you can do is make/break. the rating of the coil is where you start to calculate what size transistor or FET to use.
// ====== CONTACTS ==========================
this is isolated from everything else. it could be 1/2 amp or 1,000 amps and it has NO bearing on coil voltage or wattage.
you can have a 5 volt coil and control a 6,000 volt relay that has 100 amps.
// ===== notes =================================
your 6,000 volts times 100 amps has nothing to do with the coil rating or the power supply needed to activate the coil.
it appears you are trying to calculate coil power requirements and using coil ratings in the same formula.
LarryD:
Paralleling the contacts does increase the current capability to handel the load.
but, it is considered very bad practice.
failure of one relays will case instant and possible catastrophic failure of the second.
although the coils may activate within an acceptable time frame, using two relays with a total load that exceeds the rating of one relay can be.... shall we say 'exciting' ?
I suspect - as is so often the case - that the answer is halfway.
In paralleling two contacts - I was about to mention that yesterday - it would probably be reasonable to rate them as 50% more than a single set, to account for the various aspects of unequal sharing.
The two considerations that come to mind are arcing, and continuous current carrying. Contacts are not really meant to be subject to arcing at the best of times, and to what extent their durability varies according to contact size in not immediately obvious.
Continuous current carrying - heating - is clearly dependent on contact size - and the calibre of the contact supports and that flexing wire as mentioned. To the extent that this is unequally shared, some de-rating is appropriate.
