Appropriate relay type for 4-8 Amp water pump

Projects General Guidance
1

I am working on a home project to automate a water pump at time schedules. FYI I am not an electrical engineer, but a very experienced IT guy with passion in IOT for about 10 years now.

In the past I have created smaller project with mains and fountain pumps, led bulb etc. but this time I have to deal with a water pump that is about 1HP @220v. The ampere usage is between 4-8 amp. I am using esp32 wroom.

I am unable to decide whether I should use a 30amp electromagnetic relay or a 40 amp SSR for this. The SSR will probably need thermal dissipation, heat sink etc. The place where I will setting up things can have summer temperatures to 40 degrees Celsius.

Please give me some advice on this.

2

Most common choice would be 16A electromagnetic relay. Are there specific reasons to use something else?

3

You have 10A, 25A and of course 40A and higher SSRs available.
I would particularly go for an SSR to avoid having to add other components to suppress electrical "noise".

4

I have these modules:

https://zbotic.in/product/ssr-40da-solid-state-relay-module-3-32vdc-24-380vac-40a/

And

https://zbotic.in/product/1-channel-5v-30a-relay-module-power-failure-relay/

Since the amperage is on higher side, I am not sure which will be better. I have always used SSR for upto 2 amps interfacing mains. Higher amperage probably introduces heat and noise ?

5

I have this :
https://zbotic.in/product/ssr-40da-solid-state-relay-module-3-32vdc-24-380vac-40a/

And 10A variation of this. Which one would you suggest? Since i have never used this before I am not sure about the heatsink setup for it. I probably cannot be seated in a pvc electricals box ?

6

While Fotek is good and reliable SSR manufacturer, it's also the brand that has the most fake devices around. If I had to name the most dangerous switching device sold "online", it would be probably fake Fotek. Make some research for the subject.
The second one, traditional relay, looks much safer to me. Most of the commercial pump controls use just electromechanical relays.

7

I would go with this option and make sure it supports zero-crossing. This will help eliminate much of the EMI typically associated with magnetic contactors (relays).

8

Thing to remember is, motors can draw 4 to 6 times full load current at startup and will pop insufficient sized ssr's in an instant.

Use a contactor, that is what they are made for.

10

Can you point me to a link so i can see what it is ?

11

While i concur, this is the problem i most likely will face. This is the only SSR commonly available in the market for me. And other one is the 30A EMR (Single)

12

Here is what bluejets is referring to https://www.google.com/search?client=firefox-b-1-d&q=motor+contactor

13

Ok I see this. We have this in market. But... I don't use 3 phase motor. It's a normal single phase 1hp pump (for 220v - 240v AC). Additionally I need to switch it using a relay (via esp32). I don't understand how contractor might help in this case ? Or am I wrong ?

14

Just use one leg.

15

Or parallel all three sets of contacts.
Make sure you get the correct coil voltage.

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Tom.. :smiley: :+1: :coffee: :australia:

16

Ah i think I see what you are talking about. I just found this video and i think I can picture stuff better now.

1 Like
17

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