Need 3 phase 480v SSR with aux contact ?

[TheWaterboy]

Hello all...

I'm looking for a 480v 3ø 25+ amp Solid State Relay to replace a mechanical one beating itself to death keeping temp in a heating vessel.

I really need one with an AUX NO and NC output and 120V input (coil) signal.

I was going to put 3 Crydom relays together but though I'd ask if someone has experience with a Nema starter looking relay built for this kind of thing.

I've googled many that all looked hobby grade - looking for recommendations from successful deployments.

 

[GaryS]

A quick internet search found many manufactures that will work
Crydon is one of them they have 3 phase. However I couldn’t find any with aux contacts. But you could just parallel it with a standard relay jut to get feedback that it was turned on.
In your application I would recommend a Zero crossing turn on / off they don’t develop the electrical noise connected with random switching.
Solid sate relays are always a better choice for heating control.
Before that they had solid state relays they used mercury relays for none food grade applications.

 

[TheWaterboy]

Right .. no AUX contacts. Alas I will need to create my own then.

 

[Plastic]

Recommend CCI (Control Concepts)

Call them to describe your application.

They will guide you to a reliable, economical solution

Ccipower.com

 

[Levi G]

Have a look at Carlo Gavazzi. The RGC3 Series seems to have 120v coil 3 Phase and NO/NC Aux.
https://www.gavazzionline.com/CGNA/solid-state-relays#!

 

[I_Automation]

Right .. no AUX contacts. Alas I will need to create my own then.

The problem I see is if your AUX contact is NOT controlling 480V.


Some SSR's will control 100-480, but a lot are tighter (120 only, 200-240, 380-480)


Then there's the issue that an AUX contact on a SSR wouldn't be physically connected to the other relay 'contacts' as a relay's AUX would, so you could just add an interposing relay next to the SSR as all it would report is the PLC is energizing the output.


Plus if the AUX is planned on controlled a DC signal back to the PLC that it is ON, then a DC out SSR would be needed.



What I would do in this application is use a 3Ø SSR and add a 480V coil relay or SSR to be the AUX if there is 480 power going out the main SSR. Also a current trip relay on one of the wires to let the PLC know there is minimum level current flow to the heaters.

 

[lfe]

It doesn't make much sense for a solid state relay to have auxiliary contacts, and just because this contact closes doesn't mean that the controlled heater is actually working, the heater may have open circuit or a fuse has blown.
If you really want to know if it is heating, use current transducers like these: https://www.gavazzionline.com/pdf/E832050eng.pdf

I used them in a 1200kW kiln, the client could see the amperes of each heater on the SCADA screens.

They also manufacture current monitoring relays

 

[OkiePC]

It doesn't make much sense for a solid state relay to have auxiliary contacts, and just because this contact closes doesn't mean that the controlled heater is actually working, the heater may have open circuit or a fuse has blown.
If you really want to know if it is heating, use current transducers like these: https://www.gavazzionline.com/pdf/E832050eng.pdf

I used them in a 1200kW kiln, the client could see the amperes of each heater on the SCADA screens.

They also manufacture current monitoring relays

+1

I also recommend having a shunt trip breaker supplying the heaters with a temperature monitoring device set up to turn off the breaker if the temperature runs away. Solid state devices are much more likely fail in a conducting state than mechanical contactors and taking that into consideration for the design is important.

 

[TheWaterboy]

I had not thought about using current sensors, Thats a good idea and I'm gonna do that. Thank Guys.

 

[JesperMP]

Great advice here.
Some suggest a 4-20mA current trafo for the feedback.
If you just need a signal current/no current, then consider this one:
https://www.gavazziautomation.com/images/PIM/DATASHEET/ENG/EISH_DS_ENG.pdf

 

[Levi G]

The NRG Series from Carlo Gavazzi have all those monitoring features built-in, it seems. Communication via Ethernet/IP Profinet or Modbus. https://www.gavazziautomation.com/solid_state_relays/NRG/EN

 

[OkiePC]

The NRG Series from Carlo Gavazzi have all those monitoring features built-in, it seems. Communication via Ethernet/IP Profinet or Modbus. https://www.gavazziautomation.com/solid_state_relays/NRG/EN

That's bad a**. I haven't done any controls that needed SSRs in years, but if I ever do ...

 

[I_Automation]

Great advice here.
Some suggest a 4-20mA current trafo for the feedback.
If you just need a signal current/no current, then consider this one:
https://www.gavazziautomation.com/images/PIM/DATASHEET/ENG/EISH_DS_ENG.pdf

The one I posted the pic of is a simple N.O. relay contact that trips at a minimum current. The one in the pic trips at 0.5A, but I have a few of these on the shelf that trip at 3A that I have used in a few applications, so I always keep a few around.


Plus if I want to detect something less than 3A using these I can run the lead through the donut 2 or 3 times to double or triple the measured current.


Then they are considerably less expensive than the DIN mounted ones and can be put on the lead right below the contactor or SSR, not taking up any panel space.

 

[blkfalc4]

We use Watlow products at our place.

https://www.watlow.com/Products/Controllers/Power-Switching-Devices

 

[g.mccormick]

I have a few systems designed that I am using 4-20MA output CTs. A few benefits of monitoring the current are:
1. Calculate actual heater power.
2. You can add in logic to make sure the SSR has not failed. For some reason that I don't understand, when an SSR/SCR fails it more often than not fails "closed". With the CT you can measure the current when command is 0, and if the current is not 0 (or close) then you know you have an issue