I recently bought an sv08 and it’s been working very well so far. Except that when the heated bed hits 97-98 degrees C the circuit breaker for my house trips out. It seems to happen consistently at this temperature.
The printer still works well for printing lower temp materials like PLA, the issue seems to only happen once the bed heats above 97 degrees. So I’m guessing it’s not a faulty wire but I don’t really want to mess with mains power willy-nilly so I haven’t opened up the printer to check.
I’ve tried changing the printer config slightly to add “pwm_cycle_time: 0.02674” and reduce max_power to “max_power: 0.8”. I was hoping the issue was the printer drawing too much power for slightly too long and that being the problem. This doesn’t seem to have affected anything. Max power doesn’t seem to have any effect other than making the bed take longer to heat up and I set pwm_cycle_time based on this Voron Design page: Lights Flickering | Voron Documentation. I set it based on the 50Hz grid here in Aus but this doesn’t seem to have affected anything at all.
Does the breaker include a GFI circuit? I seem to recall that in some US jurisdictions codes now require “anti-arc” breakers in circuits supplying power to bedrooms.
Does the printer come close to the breakers capacity?
Are you comfortable swapping the location of 2 breakers in your breaker box? if so try that first.
The only thing that makes sense is that expansion of the bed is causing insulation breakdown. Only a valid explanation if breaker includes a GFI
The other even wackier thought is that changes in the PWM duty cycle as the PID control loop transitions from “Full power” to “part power” is “triggering” an anti arc circuit.
Try setting the pwm_cycle_time: LOTS higher. I’d recommend 0.2. The thermal inertia of the bed heater is such that a PWM cycle time lower than about .5 will have no detectable effect in heater performance.
I’m not an expert on how all the different kinds of circuit breakers but to my knowledge the main breakers here in Australia all work about the same way as GFCI ones do. So they will trip for over current but will also trip if the current going into the live wire isn’t the same as the current coming back out of the neutral.
I doubt it’s a capacity issue cause 240v and also because it doesn’t trip when using the max power to heat the bed only at a specific temperature. Unfortunately I’m not able to modify the breakers anyway because 240v and I’m renting this house and have room mates so can’t really mess with the power too much.
I’ll give the pwm cycle time a go next time everyone else is out of the house.
I have also emailed sovol but I thought I’d post here to see if anyone else had any info. If other people have the same problem with GFCI maybe it’s a ground fault but I don’t why that would be happening at such a specific temp.
if that’s the case I put my money on insulation breakdown in the bed module due to thermal expansion. could be anywhere on the side of the heater glued to the underside of the plate and almost impossible to diagnose.
I guess you could pull the bed out and put it in the oven @ 125 °C and measure resistance from either power lead to the aluminum plate.
Hold up… Does the SV08 use a glue on heater? My SV07 has the heater embedded into the plate. Even harder to diagnose but probably more prone to current leaks.