M140 Heater Fault Error

pete1961

@Phaedrux
I replaced the thermistor which solved the erroneous temperature readings.
I did a PID Tune and it went fine and appeared like everything was in order.
During the printing of the first part after tuning my 80AMP SSD Relay overheated, melted and self destructed. This is not the first time this has happened either.
I have the relay being controlled from the Duet2wifi Heater Output and power for the bed being supplied from a 12VDC Power Supply.
What would cause these relays to fail? What is the remedy to avoid this from happening?

droftarts

@pete1961 Most likely the PWM frequency was too high for the SSR. It's set by the Q parameter in the M950 command that defines the heater pin:
https://docs.duet3d.com/User_manual/Reference/Gcodes#m950-create-heater-fan-spindle-led-strip-or-gpioservo-pin

Qnn (optional) PWM frequency in Hz. Valid range: 0-65535, default: 250 for heaters. Max value for heaters 1000, to avoid overheating the mosfets.

Check the rating of the SSR, adjust Q as required.

Ian

Phaedrux

@pete1961 said in M140 Heater Fault Error:

12VDC

Might want to look at upgrading your bed to 24v, or even AC. Low voltage high wattage heaters have a high current draw.

pete1961

@droftarts
Can you explain how or where to adjust "Q".
I don't see it as a parameter for M307.
The SSR is rated for 80 amps.

dc42

@pete1961 said in M140 Heater Fault Error:

During the printing of the first part after tuning my 80AMP SSD Relay overheated, melted and self destructed

What make and model of SSR was it? There are a lot of fakes about, especially Fotek. The Auber Instruments ones are good.

@pete1961 said in M140 Heater Fault Error:

Can you explain how or where to adjust "Q".

It's a parameter to the M950 command that you use to assign the heater port. We suggest Q10 for driving SSRs.

droftarts

@pete1961 It's in the M950 command that defines the heated bed control pin. Yours, from your first post, is:

M950 H0 C"bedheat" Q100 T0 ; create heater #0

So it's already at 100Hz, ie switching at 100 times a second. Change it to Q10 as @dc42 suggests.

Ian

pete1961

@dc42
Thanks for the feedback.
It is a cheap Fotec but was purchased from Amazon.
So I know they are all considered junk.
I just recently purchased an Auber Relay knowing this after these other cheap Chinese ones keep melting! They have done so multiple times over the last few years.
Knowing that I will use M950. So this is in place of M307 is that correct?

Phaedrux

@pete1961 said in M140 Heater Fault Error:

So this is in place of M307 is that correct?

No. It is in addition to M307.

pete1961

@Phaedrux said in M140 Heater Fault Error:

@pete1961 said in M140 Heater Fault Error:

So this is in place of M307 is that correct?

No. It is in addition to M307.

Got it!
Let me try it!
Does it come in after M307 or before?

Phaedrux

M950 H0 C"bedheat" Q100 T0 ; create heater #0

Just edit your existing M950 command for the bed heater in config.g to change Q100 to Q10. That's all.

pete1961

@Phaedrux Just as follow up for anyone following this thread. Most all of the issues have been corrected with your excellent and quick assistance.
The only thing I still really don't like is even when changing the M950 Q100 down to Q10 the SSR still is fluctuating on and off multiple times a second with giving a scientific answer. I was hoping to see it operating on and off more like every 3 to 5 seconds.

oliof

@pete1961 you cant go below 1Hz switching frequency, but I did have success with Q1 in the past.

Phaedrux

@pete1961 said in M140 Heater Fault Error:

even when changing the M950 Q100 down to Q10 the SSR still is fluctuating on and off multiple times a second

10 times per second to be specific.

I've used Q1 when the heated bed was making my lights flicker.

Did you get a better SSR yet?

oliof

@Phaedrux a proper zero crossing SSR should avoid the flicker.

Phaedrux

@oliof I think in my case it was an interaction with the way my home automation system controls the lights using UPB.

http://www.simply-automated.com/UPB_Technology.php