I have experience this the other day with voltage back feeding through a device

[sam_sam_sam]

We have a hot glue pot and hot glue hoses and and hot glue nozzle ( all of them have heater elements in them ) machine that glue box flaps together on a product box

One note the tech support person said that the glue used was a possible cause this situation to back feed voltage as well ( I personally have my doubts about this but it would depend on what this glue is made of )

That the fuses blew on the controller board (switching power supply board section ) but did not blow the heater fuses so I put new fuses and it blew the transistor on the controller board blew apart called technical support and was told that one of the heaters RTD temperature sensor or more than one of them had shorted to the heater element and was back feeling to the controller board

Now to me this controller board has some design issues for this to happen am I wrong with this idea

[stj]

Re: I have experience this the other day with voltage back feeding through a device

nothing wrong with the controller,
your heaters should be insulated from the sensor and glue.

think about it, the heaters must be 48v or mains even to get the power.
the sensor cant handle that - at best it could operate at 30v before you blow any opamp.

[sam_sam_sam]

Re: I have experience this the other day with voltage back feeding through a device

Wrong ( but that is what I thought that was the way did it at first as well )

but they are 220 volt AC heater elements that is the problem with this crap is that the RTDs are incapacitated the in the glue tip head this is where part of the problem with this setup is ( I have seen this part of it so far) I am not sure exactly how the heater element is in the hoses are and I am not sure exactly how they are in the heated tank for the glue I have not seen these part yet

[redwire]

Re: I have experience this the other day with voltage back feeding through a device

I wonder what the insulator is for the temperature sensor. If it's epoxy, it might have melted? RTD's and thermocouples are usually protected in a stainless steel or brass thermowell, although it adds a lag in heating up so the response time is slower.
Anywhere a temperature sensor is really close to a heating element, there is a risk of short circuit.
I recall one controller board had fuses and TVS diodes on the temp sensor input, had me puzzled why bother but apparently it was common problem the sensor shorting to the heater power, and the fuses protected the board.

[sam_sam_sam]

Re: I have experience this the other day with voltage back feeding through a device

Well the ( children —> I says this because you can tell them not to do something and they will do the way they want to do it anyway ) that I work with ran it with the glue tank with very little glue in it and the other maintenance person and I think that what started this issue to being with we can not be exactly sure that what caused it but that what we think happened

[redwire]

Re: I have experience this the other day with voltage back feeding through a device

I've seen crews intentionally wreck these kind of machines so they can goof off for a shift.
Crank up the temps overheat it, bust a hose, run it dry etc. etc. Had survelliance cameras put in to prove it. Children can be brats.

[eccerr0r]

Re: I have experience this the other day with voltage back feeding through a device

surprised it doesn't log temperature or autoshutoff if it's getting too hot...

[redwire]

Re: I have experience this the other day with voltage back feeding through a device

I don't know what model controller it is, likely just a dumb PID controller? The heater+RTD sound like a custom assembly and hot glue at 150°C to 290°C would not normally wreck an RTD.

I've had guys change settings on a jammed pump, increased torque limit to 1,500 ft lbs and broke the rod. "muh the torque limit did not work!" it's supposed to be 1,100 ft lbs max. We review the logs and sure enough he jacked it up and up until it broke. It's bad when they blame the equipment for failing and I'm digging around for a fault and find nothing.

My box of shreddies just exploded, the hot glue on the bottom flap is defective. It didn't stick to the cardboard and not much glue. Bet it's these guys....

[sam_sam_sam]

Re: I have experience this the other day with voltage back feeding through a device

Like I said earlier this controller in my estimation this is not best design that I have ever seen because I think that you are asking for failure when you use main line power for the heater element and you put RTD is the same enclosure and you do not shield the RTD from the heater element

[redwire]

Re: I have experience this the other day with voltage back feeding through a device

How many watts is the heater?