Switch 220V with a microprocessor

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In summary: A relay will work but it WILL arcing and contact corrosion WILL result. A contactor will eliminate this and is more likely to last. A transistor can also be used to switch the relay but this may also eliminate the need for a uP. A 5V uP will work just fine.
  • #1
Billy_w
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Hello all,

I would like to ask how one can switch on and off a device connected to 220 V using one microprocessor output (5V). I know I should use a relay but can I use only one relay, or a cascade of two relays? Any suggestion for what type of relay I should use?

TIA,
Billy_w
 
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  • #2
Billy_w said:
Hello all,

I would like to ask how one can switch on and off a device connected to 220 V using one microprocessor output (5V). I know I should use a relay but can I use only one relay, or a cascade of two relays? Any suggestion for what type of relay I should use?

TIA,
Billy_w

One relay on the hot side of the 220V line is sufficent. You will need a transistor to drive the relay though since I doubt the uP's port has enough current capacity to drive it.
 
  • #3
Look into solid state relays (SSR), one of these will eliminate arcing and the resulting contact corrosion.
 
  • #4
Might want to look into X10.
All set up to do this.
 
  • #5
You should probably use a contactor rather than a relay for such high voltages. A simple power MOSFET is all you'd need to drive it with a 5V uP signal.

- Warren
 
  • #6
Someone mentioned switching the hot side of the 220 volt line. In the U.S. BOTH sides of the line are hot on a 220 volt circuit. There IS no neutral. A clothes dryer for example is a 220 volt device and technically has a neutral because the motor runs on 120 volts. But a 220 volt device such as a water heater has NO neutral. There is a 3rd wire run but it is a ground and is not meant to carry current. In your case it is advisable to switch both of them regardless of the device used to switch.
 

1. How does a microprocessor switch 220V?

The microprocessor acts as a control unit for the switching mechanism, allowing it to turn the 220V power on and off through its programming and instructions.

2. What is the benefit of using a microprocessor to switch 220V?

Using a microprocessor allows for more precise and flexible control of the 220V power, as well as the ability to automate the switching process.

3. Can a microprocessor handle the high voltage of 220V?

Yes, microprocessors are designed to handle high voltages and can safely switch 220V with the proper circuit design and components.

4. Are there any safety concerns when using a microprocessor to switch 220V?

As with any electrical circuit, safety should always be a top priority. It is important to follow proper wiring and grounding techniques to ensure safe operation of the microprocessor and the 220V power.

5. Is it difficult to program a microprocessor to switch 220V?

The difficulty of programming a microprocessor to switch 220V depends on your level of experience with programming and electronics. However, there are many resources and tutorials available to guide you through the process.

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