Design Help

[fifty60]

I am trying to add an on/off switch to a piece of equipment. I am using Eaton's M22 series of switches. The contacts are rated at 10A resistive and have not inductive ratings. I have heaters, compressors, fan motors, and solenoids in my equipment.

I know I have to keep the on/off switch away from my compressors and motors since they are not rated for inductive loads. The same would have to hold true for the Solenoids right?

I also have the heaters. I can remove power from the HMI and control boards, therefore removing power from the heater SSR. Or, I can place the on/off switch so that it removes power directly from the heaters as well as the HMI.

This could be seen as extra protection, by ensuring that the on/off switch directly breaks the heater load, or it could be seen as an operator hazard since the on off switches contacts will now have an extra 5A going through them.

I am leaning towards only removing power from the HMI and Control boards and avoiding the refrigeration solenoids and heaters all together. Does this seem like the more sound approach?

 

[Smart $]

Yes, solenoids are inductive loads.

Does the M22 series permit switch module stacking?

You said an extra 5A with heaters on the switch, but didn't say how much without...???

Does the HMI/control have boot up lag? If yes, perhaps a 3-pos' OFF/STANDBY/ON configuration?

FWIW, removing power from control is typically considered good enough for simply turning loads off.

 

[fifty60]

Smart$, could you better explain switch module stacking and boot up lag? I am not familiar with these terms.

the HMI and controller circuit will draw less than an amp. There are basically 4 parts of the Equipment- 1)Controller and HMI 2) Heaters 3) Compressor/fan motor 4) refrigeration solenoids

The switch will be a basic equipment on/off switch.

The entire circuit it 230V 50Hz.

 

[Smart $]

Smart$, could you better explain switch module stacking and boot up lag? I am not familiar with these terms.

Many of the common equipment switches nowadays are modular. You have an operator, which is basically the rotary mechanics, then you have contact modules which attach to the operator to complete the switching configuration, e.g. N.O contacts and N.C. contacts. In many such designs, the contact modules can be stacked, e.g. a N.O. contact module can be attached to a N.C. contact module to make, in essence, a Form C contact (N.O. and N.C. contactor) by making one terminal of each a common. If you have excessive load for one N.O. contact or two circuits with different supply, you can stack two N.O. contacts.

You didn't state the type of HMI. Many are CPU driven, and just like a computer, require boot up time before they operate. If you want to disable controls and leave the HMI booted up, standby is an option.

 

[templdl]

I would be interested to know what Eaton recommend. You did contact them of course as they would be able to provide you with the information that you need.