Please help, I want to control an invention that is 240 volts

Hello, so my friend needed help in doing their project, he wants me too control a machine that his group created by using arduino, specifically with the sound sensor with the clap code thingy.. and that invention is 240 volts... what should I use.. I saw at youtube that you need a relay for controlling appliances, and that was a 5v relay.. but what if it's a 240volts.. what should I use?

Use the 5volt relay to control a 240 volt relay. I would get a licensed electrician to build an interface box, if I was not one myself.

but what if it's a 240volts.. what should I use?

A relay capable of switching 240V at the current required. The 5V that you quote may well be the voltage required to turn the relay on. Make sure that you understand the difference between switching 240V DC and 240V AC at a particular current

[quote author=Geek Emeritus link=msg=4444720 date=1579440031]
Use the 5volt relay to control a 240 foot relay
[/quote] That's a mighty long relay.

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what we need to know is HOW you need to control that 240 .
do you need to turn if OFF and ON only ? then a relay is needed.
if you plan on variable speed, then you need something different.

I would look into an SSR. these solid state relays take the 5v directly and can handle the 240 volt.

I also assume that if your other team is working with 240 volts, they can help you with the relay selection. AND any 240v wiring, enclosures, etc.

A motor is a unique thing and not all relays are designed to work with motors. we do hobby work so are not as familiar with the 4 ratings of relays, motors, AC and DC and lighting.
once you move into the commercial equipment realm, things like Lighting Contactors become specific devices with special materials on the contacts that are designed specifically for the type of load that is controlled.
Also, relays have a separate rating for motors. in the hobby range, these are not usually listed.

As another note, once you get into the higher fractional HP motors and larger, you move to a motor starter. it is a unique relay type. the beauty is that your hobby relay can switch power to control a proper relay for larger devices, often less than 1 amp for the control signals and often at the same voltage as the device being controlled. most typical in the USA is a control signal of 120VAC or 24VAC on the coil of the relay, even when switching 230, 208 or 480 volts.

dave-in-nj:
do you need to turn if OFF and ON only ? then a relay is needed.

Yes only on and off

................

Thank you for the repliesss, really appreciate it

a quick check on eBay shows the mechanical relay modules can control 250 VAC @ 10A, and the SSRs can switch 240 VAC @ 2A

The simple fact we’re talking about this relay & minutiae indicates you may be working beyond your safe skills.

You can buy an approved, safe mains relay switching module (insulated & covered), and control that - or pay a skilled ‘automation’ sparkle to help you,

Tha long term risks of a bad decision are loss of insurance, friends or death.

Much more to mains connected device's design than Ebay recommendations.

This is probably a stupid question but uhh.. So I got this 5v relay connected it to 5v and gnd in arduino then I powered up the Arduino using a 9v battery... and the relay doesn't turn on.. is it because of the 9v battery? should I use a 9v relay instead?

Selimx123:
This is probably a stupid question but uhh.. So I got this 5v relay connected it to 5v and gnd in arduino then I powered up the Arduino using a 9v battery... and the relay doesn't turn on.. is it because of the 9v battery? should I use a 9v relay instead?

and also the relay actually turns on when I plug the arduino to the computer, it's just when I powered it up with a 9volts batt, it doesn't have that click sound to indicate that it's on

What is the voltage of the battery when under load powering the Arduino and relay ?

9V will work but a "regular 9V battery" won't last long.

A 5V relay coil needs 5v. But, you have to be a little careful about the coil current because the Arduino's on-board voltage regulator can overheat and shut-down.

It might work but it's better for the relay (or anything that requires "power" to have it's own power supply (or the Arduino and other circuity can share the same 5V power supply). You can try USB power if you're not getting enough power from the battery..

Also, you can't directly-drive a relay coil from an I/O pin. (You can drive a relay board or relay module if it has the right driver circuit.)

What relay or relay module are you using? Please give us a link to the specs. Please show us a schematic of your wiring. Hand-drawn & scanned is OK is OK

Check the 5V with a multimeter to see if it's "holding up". Also, check the 9V battery, with everything connected & running.

If the supply voltages seem OK measure the voltage directly across the relay coil when you expect it to be on. If you don't have any voltage, check the Arduino's I/O pin to make sure it's switching between 5V and 0V. Try to trace-down where you're loosing the on/off "signal".

You can also check the relay module by itself (without the Arduino) by "triggering" it directly from the 5V power supply.

You may need a 240v contact relay to control the machine. Figure that out and work back toward the arduino from there. You might use mechanical relays or solid state relays in the mix.

INSULATION
ISOLATION
PROTECTION

DIY

https://www.google.com/search?q=arduino+mains+relay&rlz=1C9BKJA_enAU768AU768&hl=en-GB&prmd=isvn&sxsrf=ACYBGNSCKMX26wsxEs3bDXXv5Sw6ZPmVgQ:1579639995172&source=lnms&tbm=shop&sa=X&ved=2ahUKEwje1KPGyZXnAhVFX30KHVSCDfAQ_AUoAnoECA4QAg&biw=768&bih=911

or something like this...
https://www.google.com/shopping/product/1?q=arduino+power+switch&rlz=1C9BKJA_enAU768AU768&hl=en-GB&biw=768&bih=911&tbs=vw:l,ss:44&prmd=sivn&sxsrf=ACYBGNQnbBKYz1ssJQ6dHRUZJsZRUWXqpA:1579640049074&prds=num:1,of:1,epd:17978963557171576397,paur:ClkAsKraX1dElrnXEz1tGOHSfDwfsMgznLWk23HicYBuX0BA7rGXGLuEEzCWL30KDNxigQ2Thm9fk9hXZdDbTrQbOGGZvtn8GilnXvv31l-4t5tcHnTxXXOYoxIZAFPVH73IKaKZy7kDZozc3J_guKYgfvoiVA,prmr:1,pid:17978963557171576397,cs:1

https://www.google.com/shopping/product/1?q=arduino+power+switch&start=20&sa=N&rlz=1C9BKJA_enAU768AU768&hl=en-GB&biw=768&bih=911&tbs=vw:l,ss:44&prmd=sivn&sxsrf=ACYBGNQsALlo6Wne9pOBpFXmrYpIRGwwCw:1579640299434&prds=num:1,of:1,epd:6888996372688174985,paur:ClkAsKraX-gC4t1rJLHDE8H0ZuaWTp065GlBbycgaJqllBl3DrbfE13dzmN2IaqeguI1dQP90m1TteCfhYyP4VZ05WpzPScrnfon83S8UUs05qMg30nXABJZNBIZAFPVH70Dly0RqMuaBnjkG3Rs4-aBy7KkAw,prmr:1,pid:6888996372688174985,cs:1&ved=0ahUKEwitsK7XypXnAhWZSH0KHa0TC8c4FBCCNgjXBA