Why doesn't OP post the relay part no. we did ask him to post it.
This won't get any where, you guys can talk about relays and how they work and how wonderful clicking sound it makes and share relay secrets between each other and still the OP's relay is overheating.
He says it's 12VDC and he is giving 9V and still the relays are warming up. This does make any sense.

We can go on and on and talk about relays and everything but without OP relay's part no. none of us can decide anything and I really love to see how the OP is connecting the relays.

Please...please ..just give us the relay specs, or show us a picture or draw a diagram in MS paint on how you made the connection so we can solve this mysterious relay overheating problem

 

Why doesn't OP post the relay part no. we did ask him to post it.
This won't get any where, you guys can talk about relays and how they work and how wonderful clicking sound it makes and share relay secrets between each other and still the OP's relay is overheating.
He says it's 12VDC and he is giving 9V and still the relays are warming up. This does make any sense.

We can go on and on and talk about relays and everything but without OP relay's part no. none of us can decide anything and I really love to see how the OP is connecting the relays.

Please...please ..just give us the relay specs, or show us a picture or draw a diagram in MS paint on how you made the connection so we can solve this mysterious relay overheating problem

Greetings natiz,

I think we all share R!f@@'s frustration. Please, will you let us know what markings are present on the outside of the relay so that we can get to the bottom of your overheating relay problem. We all want to move on.

Thanks,
hgmjr

 

can anyone of you tell me if I use resistor to drop voltage where relays can work.. is this will help me in maintaning temperature of relays ... so they can work for continous work till month or more?

 

Im running CONTINOUSLY one 9VDC with 1ampere adapter connected directly to a 12VDC coiled relays since last four days to test. Now still its running and temperature of relay is same as If i put my finger on it, it wouldnt burn me but I feel its hot and same as transformer is hot but I can easily place my finger on it for 15 minutes and more easily... What do you think now will it work same for next 1 month if I leave as it is?

 

My relay specification (on it) :

Clion t90
hhc67e-1z-12vdc
30/20a 250vac
/28vdc

 

http://www.electrical-relay.com/1-pcb-relay-4.html
http://www.electrical-relay.com/pdf/T90.pdf

Nothing obvious to me.

Coil current should be 78mA (.93W/12V). That might lightly load a 12VDC unregulated wallwart.

natiz,
Did you ever actually measure the output voltage of the power supply?

Ken

 

That relay needs to be mounted in a printed circuit board that has wide and thick traces connected to the terminals. The traces must be on the other side of the board from the relay, and need to have air flow over them to provide cooling.

If you simply have insulated wires connected to the relay, it will overheat, as there will be no place for the heat to go except radiating out through the plastic case.

 

thanks much now I come to know it needs only 78mA with 9V DC or 12VDC.. I measured my power supply .. it gives (according to meter) only 9VDC.. I dont know how to check amperes...
PLEASE TELL ME WHAT THING I CAN USE BETWEEN RELAY AND VOLTAGE SUPPLY TO REDUCE AMPERES ONLY. because its already gives me 9VDC but 1 ampere .. so I just need to reduce amperes only...

 

natiz,

The relay will draw 78mA at 12vDC because the coil resistance is ~150Ω. At 9VDC the relay will only draw 60mA (9V/150Ω). The relay coil resistance limits how much current is drawn from the power supply. The power supply current rating (1A in your case) is the "maximum" current it is designed to supply. To better understand the relationship between voltage, resistance, and current, you may want to look at the e-tutorials on this forum. For example: http://www.allaboutcircuits.com/vol_1/index.html

Ken

 

I dont know how to check amperes...

First, you say you don't know how to check amperes.

because its already gives me 9VDC but 1 ampere

Then you say it is taking 1 amp.

These two statements seem to be in conflict.

hgmjr

 

no confilction .. I just confirmed it from shop keeper from where I bought power supply... please answer me what to use (RESISTOR??) to reduce amperes only? from 1AMP to 78mA

 

If you use a resistor to limit the coil current, it probably will no longer work.

You need to MOUNT THE RELAY in a CIRCUIT BOARD that has WIDE AND THICK TRACES WITH AIR FLOW to remove the heat from the relay.

This is the third time that I have written basically the same information. I hope you actually READ it this time.

 

no confilction .. I just confirmed it from shop keeper from where I bought power supply... please answer me what to use (RESISTOR??) to reduce amperes only? from 1AMP to 78mA

Ok. So your power supply is capable of delivering 1 Amp of current. However the relay draws only 78 milliamps. A quick calculation of the power in the relay coil is around 0.9 Watts. This power is resulting in a build up of heat that needs to be dissipated through some sort of heatsink. Sgtwookie's advice on how to mount the relay would solve the heat problem by drawing the heat away from the relay and thus keeping it cool. No resistor is needed nor advisable.

hgmjr

 

SgtWookie,

Do you have any references for best-practices on mounting relays on PCBs? I couldn't get anything (except "space them") in a Google search.

Ken

 

thanks SgtWookie, I got your advise. Now according to you all, I just need to mount it on a circuit board only to manage with heat even I give it 1000mA instead of 78mA. ok I try to use some small fan over relay for reducing heat to check it further in same condition of voltage.

 

OR can I use some heat sinker plate pasted on upper plastic of relay with some glue so that heat can cross through heat sinker plate? as well as mounted on circuit board for further precaution?

 

SgtWookie,

Do you have any references for best-practices on mounting relays on PCBs? I couldn't get anything (except "space them") in a Google search.

Ken,
No, I don't offhand.
However, it's a given that the relay coil will be dissipating power, and that the coil is sealed up inside a plastic case that won't conduct heat very well. The only "real" path for the heat to travel is through the connecting leads.

12v x 78mA = 936mW; basically 1 Watt. So, you would need enough thickness of the traces and board space to conduct/convect/radiate that heat into the surrounding spaces, or to air.

If the heat is not conducted away from the relay, it will overheat.

This website has lots of info on designing PCBs:
http://www.smps.us/pcb-design.html

 

thanks SgtWookie, I got your advise. Now according to you all, I just need to mount it on a circuit board only to manage with heat even I give it 1000mA instead of 78mA. ok I try to use some small fan over relay for reducing heat to check it further in same condition of voltage.

The relay coil has a resistance of 150 Ohms.
If you supply it with 9v, then you will have a current through the relay coil of 9v/150 Ohms = 60mA, and you will be dissipating 9v x 60mA = 540mW power in the relay coil.

 

OR can I use some heat sinker plate pasted on upper plastic of relay with some glue so that heat can cross through heat sinker plate? as well as mounted on circuit board for further precaution?

I suppose you could do that if you wanted to, but the most effective way to get the heat out of the relay is by the wire leads that connect directly to the coil. If you solder them to really wide, thick traces on a PCB, and allow good air flow, that should take care of the heat problem. Even mounting the PCB vertically and simply providing slots or holes for air circulation should be sufficient; the heat from the traces will heat the air, causing it to rise away from the board. Cooler air will flow in to take the warm air's place.

Plastic is not a very good conductor of heat/cold when compared to metal.

Gluing something to the top or sides of the relay would be messy, and it would make replacement of the relay more complicated when that becomes necessary.

 

Another drawback to the use of glue to hold the heatsink onto the plastic housing is that it will degrade the efficiency of the heat transfer from the plastic housing to the metal heatsink. Ordinary glue is not likely to be an efficient heat transfering material.

hgmjr