Folks,
I have a project where I'd like to switch a 110VAC 1-HP 10A motor on and off using a SSR and a Nano. If was thinking of getting one rated at 50 to 60A to give myself plenty of headroom for the in rush current. Will I need a heat sink for the SSR?
Initially I was going to use a relay but I couldn't find any that I thought would really handle the current. Does anyone know where I can find 5V logic 15A or 20A relays?
Anyway, let me know your thoughts people.
Best,
Tony
tperry724:
Folks,I have a project where I'd like to switch a 110VAC 1-HP 10A motor on and off using a SSR and a Nano. If was thinking of getting one rated at 50 to 60A to give myself plenty of headroom for the in rush current. Will I need a heat sink for the SSR?
Initially I was going to use a relay but I couldn't find any that I thought would really handle the current. Does anyone know where I can find 5V logic 15A or 20A relays?
Anyway, let me know your thoughts people.
Best,
Tony
You are have to drive the relay with a transistor, so why do you care about the coil voltage? Check any component distributor such as Digi Key, Mouser, etc.
Paul
Test your SSR by hand. If It's too hot, then it needs a heat sink. Best if copper or aluminum and if you can a thin layer of heat sink compound to ensure 100% contact between the SSR and the heat sink.
@Paul You dropped a word in your reply and I wasn't sure about your response. What would you recommend I do? Always looking for input from folks. Again, I thought an SSR would be a good option for this application. Do you think a relay would be better. No matter which I choose I was hoping to switch them directly from the Nano. I have very limited experience with transistors. I'm still very new to coding, and Arduino. I'm pretty good with household wiring so I'm not uncomfortable working with 110AC. Thank you for responding.
@Paul When I say 5V logic, I think I mean the coil voltage, as you stated. I want to drive directly from the Nano, which doesn't give me a lot of current to play with. That's why I thought the SSR would be a good idea. But I'm newer to all of this. I have used those blue relay modules that have 1,2,3,4 or 8 channels. Which I've driven from an Uno without much problem. However, I was switching 19VDC, not 110VAC. Were you trying to tell me that most relay's that I could use for this project I would need a transistor? Would it be because of the coil current? Sorry for all the questions. Just trying to learn.
tperry724:
@Paul When I say 5V logic, I think I mean the coil voltage, as you stated. I want to drive directly from the Nano, which doesn't give me a lot of current to play with. That's why I thought the SSR would be a good idea. But I'm newer to all of this. I have used those blue relay modules that have 1,2,3,4 or 8 channels. Which I've driven from an Uno without much problem. However, I was switching 19VDC, not 110VAC. Were you trying to tell me that most relay's that I could use for this project I would need a transistor? Would it be because of the coil current? Sorry for all the questions. Just trying to learn.
You CANNOT drive such a relay from any of the Arduino family!!! A SSR is controlled by a LED with a current limiting resistor inside the SSR. Exactly the same as running a LED with a current limiting resistor from any Arduino pins.
I have built several projects using SSRs. One controlled a 500 watt drying oven and needed a heat sink. Another is in my home irrigation system. The SSR controls a 2" solenoid valve. No heat sink. Both projects use a Nano to control the SSR controlling the 120 VAC.
Mechanical relays require some type of transistor circuit because of the current requirements of the relay.
Paul
By the way, there is no inrush current with an SSR because they switch on as the current crosses the 0 (zero) voltage line.
Paul_KD7HB:
By the way, there is no inrush current with an SSR because they switch on as the current crosses the 0 (zero) voltage line.
I'm not sure I agree. Are you talking about the SSR turning on the 1 HP motor? If so there is definitely inrush current and lots of it. Especially if the motor is under load.
The zero crossing helps reduce electrical noise because (as you mentioned) they turn on at the mains Zero crossing.
However when the SSR turns on the motor, the motor is not yet moving so the current to get the motor running is many times the running current.
This paper might help you and the OP: Whitepaper: SSR powering motor
@Paul Thank you for the guidance. I think a SSR is the way to go.
@JonRob I was thinking of using somehting like a 50 or 60A SSR. Based on the whitepaper you attached, it looks like a good option.
Are there any brands of SSR you trust that are on the inexpensive side? Amazon has many in the $15 range. The Crydom brand SSR looks to be $55 or so. Maybe something in between in terms of cost. Or should I just go with the name brand?
Thanks again.
Happy Holidays.
MFG
SUPCO DP401202
VENDOR
[SUPCO DP401202](Supco Contactor, 40A, 120V, 2 Pole DP401202 | Zoro %26 HVAC Equipment %2B HVAC\")
(in case the SSR can't take the heat)(you can use a standard SSR to turn on the mechanical contactor)
@raschemmel Thank you.
Your welcome