120vac 750w Bed heater/SSR combo and PID mode
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Hi,
Can a 120vac 750w bed heater/SSR combo be run in PID mode?
Will the SSR suffer from the way the heat is controlled?
Thanks.
Frederick
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I am running a 600W heater with SSR in PID mode. The PWM frequency is 10Hz. Te printer is fine, the lights in the house not so much. Disco-printing
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@sigxcpu said in 120VAC Bed heater/SSR combo and PID mode:
I am running a 600W heater with SSR in PID mode. The PWM frequency is 10Hz. Te printer is fine, the lights in the house not so much. Disco-printing
Thanks much. Good to know.
Frederick
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I run a 750W bed heater under PID control with an SSR. IRIC, the frequency is set to 20 Hz. No issues at all. My SSR has a built in zero-crossing detector.
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@mrehorstdmd said in 120vac 750w Bed heater/SSR combo and PID mode:
I run a 750W bed heater under PID control with an SSR. IRIC, the frequency is set to 20 Hz. No issues at all. My SSR has a built in zero-crossing detector.
I checked on the M307 command and it talks about PWM frequency but it doesn't mention (at least that I see) the units.
The M307 for the bed heater reports the frequency is the default.
So how did you decide on 20Hz and how do you set that?
Thanks.
Frederick
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The default for bed heater is 10Hz. You can set it with M307 and "F" parameter.
Source for 10Hz:
Source for "F" parameter:
https://duet3d.dozuki.com/Wiki/Gcode#Section_M307_Set_or_report_heating_process_parameters -
@sigxcpu said in 120vac 750w Bed heater/SSR combo and PID mode:
The default for bed heater is 10Hz. You can set it with M307 and "F" parameter.
Source for 10Hz:
Source for "F" parameter:
https://duet3d.dozuki.com/Wiki/Gcode#Section_M307_Set_or_report_heating_process_parametersThanks very much.
Frederick
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The line frequency is 60 Hz, so I thought some value that's not too low, and there isn't much point in switching it higher than the line frequency. The bed is massive and temperature changes are slow, so even 20 Hz is probably faster than it needs to keep the temperature well regulated. I added an F20 parameter to the M307 statement for the bed heater to set the frequency.
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@mrehorstdmd said in 120vac 750w Bed heater/SSR combo and PID mode:
The bed is massive and temperature changes are slow, so even 20 Hz is probably faster than it needs to keep the temperature well regulated. I added an F20 parameter to the M307 statement for the bed heater to set the frequency.Thanks much.
I made my first print with a heated bed. No warping/curling using PLA and good adhesion - almost too good - it was a little hard to work loose.
Frederick
