PID, PWM and SSR
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I was wondering how to select an SSR that can work with the DuetWifi and PID and PWM for bed temperature control.
My new printer design is going to be using a silicon heater (probably a custom one from Keenovo), that I am hoping to get around 1W/cm2. That would place it around 14.3A at 24V. I might later end up going larger, and I would like to have a certain safety factor on the amperage anyhow.
I currently have one of these: http://imgur.com/a/gICKy
But I am not convinced it is very good on any account, the similarity in this breakdown: https://www.youtube.com/watch?v=DxEhxjvifyY is a little worrisome.
So I was considering one of these: http://www.digikey.ca/product-detail/en/crydom-co/CKM0620/CC1721-ND/1643035
Which has the added benefit that it is din rail mounted. In the Datasheet it says maximum on / off time is 1.0ms. But it doesn't list any frequencies otherwise.
EDIT: I just wanted to add that I found another one: http://www.digikey.ca/product-detail/en/crydom-co/DR2220D30U/CC2258-ND/5699192 that rates 1kHz on PWM.
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To my understanding Mosfets handle PWM better than SSR's. That being said you can get a mosfet driver board much cheaper than an SSR.
handles up to 25A supposedly, 12-24V input and uses your bed output to control it. I should add that I use this, it's dead silent and barely gets warm for PLA bed temps.
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I cover this at https://duet3d.com/wiki/Connecting_a_bed_heater#Bed_heater_driven_using_a_Solid_State_Relay. For DC bed heaters, us the Auber Instruments SSR.
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Why not consider mains voltage, strangely it does get rid of far more headaches than it creates, and the performance is superb. Eg. 5mm tooling plate 330mm circular bed goes from ambient to 120 deg C in 3 mins 20 seconds.
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Hi,
I'm using the Auber Instruments MGR-1DD80D100 that DC42 recommend on the wiki and I've nothing to say about it.
It does its job perfectly, beside an almost imperceptible vibration caused by switching that doesn't affect anything.
I use it with the makerfarm 12v heatbed 12x12in -
I'm not sure if it's been mentioned yet or not that not all SSR's work with DC voltages, some are AC only. Pretty much if it doesn't have a DC current rating specified I would assume it's AC only.
Jeff
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I am currently using a DIN-Rail Mount Long-Life High-Amp Relay, SPST-NO, 4-32V DC, 20A @ 600V AC,
6323T42 from mcmaster carr
I have had my keenova 110 AC bed running for the last 4 months.
