# Why is 24V used in control circuits?

## Why is 24V used in control circuits?

Typically, control devices are large and operate on the same voltage used to power the motors. By using 24V DC as a control voltage, manufacturers can increase reliability. One reason for this is that these power supplies operate with limiting circuits to protect against short circuits.

## Is 24 volts better than 12 volts?

In an electric vehicle the power usually comes from the battery, and is converted by the motor into energy. Electrical power is volts multiplied by amps so that 40 amps from a 12v battery is 480 watts. so a 24v system is always better than a 12v system – provided you can physically fit two batteries.

How does a 24 volt thermostat work?

The power is supplied by a transformer, and when the thermostat makes contact between the 24 volt power and one or two of the other wires, a relay back at the heating/cooling unit activates the corresponding heat/fan/cool function of the unit(s).

Why was 24 VDC popular for industrial control panels?

Users find that 24 Vdc is popular for many reasons: Safety: Personnel are less likely to be shocked at this voltage. Regulatory: NFPA 70E and OSHA consider 50 V and above as hazardous. Power delivery: Most automation devices are low power and draw small reasonable currents at 24 Vdc.

### Who uses 24V?

We sometimes use 24V battery systems in larger trucks and busses due to the vehicle’s higher power needs and long cable runs. You can also see 24V used in larger boats and some RVs with elaborate solar systems. Another typical application for a 24V system is on trolling motors for fishing boats.

### What is more efficient 12V or 24V?

Because 12V batteries use two times the amperage at a given power draw, they are less efficient than a 24V battery due to resistive losses.

What does 24V mean?

What it means is that if you connect a 12 volt battery to the controller, it will automatically produce just enough voltage to charge a 12 volt system. If, however, you INITIALLY connect a 24 volt battery array to the controller, it will produce just enough voltage to charge a 24 volt battery array.

Does a thermostat need 24 volts?

Yes you are absolutely correct, typical Heating and Cooling thermostats operate at 24 volts AC. If we said DC somewhere that was a mistake. We do make a distinction between line voltage which is 120 V AC and the thermostat which powered voltage reduced by a Transformer to 24 V AC.

## Will a 24v thermostat work on 12v?

Most any battery operated thermostat will work for that system. You would only use the R and W connections on most units. You need to find something electronic, battery powered with relays – the lower voltage might cause problems with triacs found in cheaper t-stats.

## Can you get a shock from 24VDC?

Yes, you can get electrocuted at lower voltages but you’d have to really work at it. Most high voltage circuits that you are likely to come in contact with have an internal resistance that is high enough that they can not source a high enough current to do damage, that’s why you perceive high voltages as safe.

What should the voltage be for a 24 volt HVAC system?

Just remember to turn off the power to your furnace first! Normal voltage range for 24 volt HVAC systems is 20 to 30 volts. Normally if you are in that range to the upper/lower bound of accuracy of your measuring equipment you’re fine. An induction transformer will read higher when lightly loaded.

Why is my furnace not getting 24 volts?

If you are not getting any voltage to the contactor coil then this could be a blown fuse on your furnace or air handler control board. Please see the picture of the control with the fuse below. If the fuse on your control board is blown then you probably have a short in the thermostat wires or another control in the furnace or outdoor unit.

### Which is better 24V AC or 24V DC?

Additionally, 24V DC has higher ride-through capabilities, allowing control devices to better survive voltage sags. Mechanically, 24V DC devices do not require laminations and oils typically used in AC coils, which can cause contacts to stick.

### What can you do with a 24 volt transformer?

A 24-volt transformer is typically used as a control device to turn a higher voltage, generally 120 VAC, into a lower working voltage for switches or relays, such as in a furnace thermostat transformer.