Why can’t I find the industrial equivalent of the prototyping component?

Thread Starter

tlewick1

Joined Dec 3, 2016
26
I’ve made various projects using prototyping programmable controllers (like Arduinos) in the past, but I’m working on something now that will be in the industrial setting. I want to use an industrial controller having the components mounted on a din rail. In some situations this will simplify things— some components needed 24V and I had to use transistors to handle the higher voltage. But there’s one thing I can’t find a product for:

A din rail mounted power mosfet.
(The title of the post makes it sound like I’m calling a mosfet a prototyping component. I’m not.)

The project has a small resistance heater. At 24V, I’ll need to limit the current to 1A. The controller will monitor the temperature and limit the current accordingly (from 0-1A). I was thinking I could connect an analog output logic pin to a MOSFET to limit/control the current going to the heater (nichrome wire.) Why can’t I find any din rail mounted mosfets? I can find solid state relays and octocouplers, but I don’t think that’s what I need, and all of them have fairly high minimum output voltages (5V).

What am I missing here? I could make a circuit and put it in an enclosure, but I expected to be able to buy it readily.
 
Last edited:

panic mode

Joined Oct 10, 2011
2,715
what do you expect this MOSFET to do? for switching applications there are solid state relays.

one of the problems of individual MOSFET (or BJTs or LEDs etc.) is that it is not yet "industrial ready". for example gate needs some conditioning because it cannot tolerate 24V. by adding those additional components, product is no longer a "mosfet", it is a device that contains that part as well as many others. IF what you are looking for does not exist - make it your self. there are prototyping boxes or DIN rail mountable PCBs just for that. some are open frame (personally never fan of those in industrial setting).
 
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Thread Starter

tlewick1

Joined Dec 3, 2016
26
what do you expect this MOSFET to do? for switching applications there are solid state relays.
Most of the thermostats in the picture above were designed to trigger relays, i.e. on/off active action of larger heating/cooling systems. I want something what will go from 0-1A output (and anywhere in between.)
After your reply, I searched some more for thermostats, and found some that had PID SSR pulse “Outputs: Voltage pulse for SSR (5 Vdc / 25 mA),”
Isn’t that logical level output at that point? I still need something that will let me output a range of current from nothing to 1-2A.
 

strantor

Joined Oct 3, 2010
6,782
SSRs are often used in industrial heating applications with large thermal mass. A PID temperature controller will monitor temperature via thermocouple and switch a SSR on and off. But for applications with low thermal mass (like your nichrome wire, assuming it is free floating in air) which can drop dramatically in temperature within an instant of removing power, you need some kind of power controller.

For AC power, A phase angle fired SSR would probably be what you need.
https://www.hbcontrols.com/proportional-output

For DC power, if you use a sufficiently high frequency (100Hz + ought to do it) you should be able to use a regular SSR.

If you're still looking for an arduino-style controller in an industrial package, check this out:

https://www.automationdirect.com/ad...roductivity_open_(arduino-compatible)#start=0

They have made an arduino-compatible PLC processor which uses regular PLC I/O cards, including a PWM output card:
https://www.automationdirect.com/ad...o-compatible)/industrial_i-z-o_(p1k)/p1-04pwm

And several options for temperature input (thermocouple, RTD, analog, etc.) Just look around there you will probably find what you need.
 
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