Need help for my simple Container Overheat Indicator

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1

I have the following setup below for my project Container Overheat Indicator .

Materials:

1pc TC4-M1A temperature controller

1pc 12v 3PDT Relay

1pc 12v LED Warning Light

Algorithm:

  1. The Temperature Controller will read and display the temp. of the environment

  2. If the temp reading reaches 70 deg C, the temp controller will turn on the 3PDT relay through its own Relay Output

  3. The 3PDT relay will turn on the 12v LED Warning Light as long as the temp reading is 70 deg C or above

  4. The 3PDT (and the Light), will be turned off by the Temp Controller if the temp reading is already below 70 deg C.

Questions:

  1. The datasheet does not indicate that the Relay Output of the Temp Controller may be used for DC loads …

It only says:

“Relay Output: 3A/250V AC Capacity”

However:

I still tried connecting the 12v 3PDT Relay to the Temp Controller’s Relay Output.

And everything works fine, and the algorithm was followed seamlessly .

Is it ok to continue doing that ? Is there going to be any problem if I continued doing that?

  1. Do I need to use a flyback diode for the 3PDT relay?

I uploaded below my setup diagram and the Temp Controller’s images and sheets .

Thanks !

2

I still tried connecting the 12v 3PDT Relay to the Temp Controller’s Relay Output.

And everything works fine, and the algorithm was followed seamlessly .

Is it ok to continue doing that ? Is there going to be any problem if I continued doing that?

You're OK. The TC4-M1A relay output can certainly handle the 12v/160 ohms = 75 mA load of the Omron relay coil given the rating of 3A/250VAC. In fact I don't see why you need the Omron relay and it's wallwart at all. You could switch your LED lamp (and wallwart) via that output of the TC4-M1A temperature controller directly.
  1. Do I need to use a flyback diode for the 3PDT relay?
Nope. And if you did the Omron relay datasheet says it has one built in.
3

Also, for an overheat indicator, shouldn’t you be using the Alarm output instead of the Control output?