240v relay tests.

[Marvin]

Have been going through relay alternatives for my heating controls.

 

Realised that some relays would be energised for hours and wanted to see how they coped. So here are my test results and questions.

 

Thanks for looking.

 

Equipment:

 

 

Relays I'm testing:

 

Results:

 

My results based on ambient room temp 23C.  All relays not under load. All relays 240v coils.

 

BG CUC20 

Watts when energised  2.2 steady.

Temp after 10 mins  36C

 

BETA 

Watts when energised 1.7 steady

Temp after 10 mins  35C

 

OMRCIT

Watts when energised 4.7 to 4.1falling

Temp after 10 mins 67C

This one has a neon.

 

Is the high temperature of the OMRCIT, when not under load, a concern?

 

Bet you can guess which one cost the least.

 

[ProDave]

I used Findr relay from CPC with a small plug in din rail base.  I never measured the coil power consumption, but none seemed to get hot, certainly not 67 degrees hot. and they were less than £10 for relay and base.

[Marvin]

33 minutes ago, ProDave said:

I used Findr relay from CPC with a small plug in din rail base.  I never measured the coil power consumption, but none seemed to get hot, certainly not 67 degrees hot. and they were less than £10 for relay and base.

Thanks for that. 

 

Anyone:

If the coil resistance is 15.92 kiloohms and the voltage is 220 to 240, what is the Wattage?  Is it about 3 Watts???

Edited December 29, 2021 by Marvin

[ProDave]

2 minutes ago, Marvin said:

Thanks for that. 

 

Anyone:

If the coil resistance is 15.92 kiloohms and the voltage is 220 to 240, what is the Wattage?

V²/R

=3.61W

 

Might be less as it's an inductive load on ac

[Marvin]

1 minute ago, ProDave said:

V²/R

=3.61W

 

Might be less as it's an inductive load on ac

Your reply is near enough for me. Thank you.

 

The "hot OMRCIT ones" were from china. The Beta ones I have had for some time.... The heat in the OMRCIT ones travels along the connectors to the terminals where the cables connect and I have measured over 70C just sitting on the kitchen side!

 

Shut in a steel box with several in a row, with a load crossing the terminals, I think they would rise even higher and may melt the wire sleeving, even using heat resistant wire, so I am not going to use them, especially when they could be energised for hours at a time! 

[Temp]

5 hours ago, Marvin said:

OMRCIT

Watts when energised 4.7 to 4.1falling

Temp after 10 mins 67C

This one has a neon.

 

Is the high temperature of the OMRCIT, when not under load, a concern?

 

Is it possible the neon is fooling the IR monitor or does it feel that hot to the touch?

 

 

[SteamyTea]

Anyone done a similar test on solid state relays?

 

2 hours ago, Marvin said:

what is the Wattage

Print this out and keep in back pocket.

[Onoff]

10 minutes ago, SteamyTea said:

Anyone done a similar test on solid state relays?

 

Print this out and keep in back pocket.

 

Or get the T-shirt / mug.

[Marvin]

29 minutes ago, Temp said:

 

Is it possible the neon is fooling the IR monitor or does it feel that hot to the touch?

 

 

No. This was the bottom plate temperature. Hotter than the rest of the relay, measured up through the surround.

[Radian]

52 minutes ago, SteamyTea said:

Anyone done a similar test on solid state relays?

 

Never really considered it. Opto coupler LED is nearly always the only load on the control side so I would think 60mW max (3V@20mA)?

[Temp]

2 hours ago, Onoff said:

 

Or get the T-shirt / mug.

 

or just remember 

V=IR

P=IV

and work the rest out in your head ?

 

[Onoff]

2 hours ago, Temp said:

 

or just remember 

V=IR

P=IV

and work the rest out in your head ?

 

 

Being pedantic...

 

With a relay coil shouldn't R be substituted by Z? 

 

 

[SteamyTea]

7 hours ago, Onoff said:

With a relay coil shouldn't R be substituted by Z

Don't forget J and K

[ProDave]

14 hours ago, SteamyTea said:

Anyone done a similar test on solid state relays?

They DO get hot, that's because they have a finite non zero "on" resistance so there are losses proportional to the load drawn.

 

The SSR for my solar PV dump is attached to a reasonable size heat sink and gets just pleasantly warm at full load.

[Temp]

23 hours ago, Onoff said:

 

Being pedantic...

 

With a relay coil shouldn't R be substituted by Z? 

 

 

 

Only for a little while ?

[Marvin]

14 hours ago, ProDave said:

They DO get hot, that's because they have a finite non zero "on" resistance so there are losses proportional to the load drawn.

 

The SSR for my solar PV dump is attached to a reasonable size heat sink and gets just pleasantly warm at full load.

Yes. Hense the higher the power to energise the hotter it gets. ..

Edited December 30, 2021 by Marvin