Quiksilver225
New member
There seems to be a lot of confusion and terminology used to describe how a PC can work on a power source other than US 110V 60Hz supply. Words such as converters, changers have been used and there’s a few other issues that need a bit of clearing up. So here goes, this is what you need to run a PC from a non US power supply, and safely. If your power supply is 240V or 230V just use the 220V figures for now, makes it simpler.
Lets start with what the PC (7424) needs, electrically:
Power
120 VAC, 50-60 HZ/120 VDC
Motor Amps : 3.7
No-load Speed
2,500-6,000 OPM
If you apply 220V to a 120V appliance it WILL be dead in a matter of seconds. We need to reduce the voltage from 220V to 120V and for this, we use a transformer. Like most things, size does matter, and we need to work out what type and size of transformer we need to run the PC. Too large and we need a forklift to move a transformer, too small and we run the risk of not starting the PC at all.
Transformers are rated in VA, (not WATTS) and lo, the figure is derived from multiplying the Voltage (the V bit) and the Amps (the A bit). So the PC needs 120(V) x 3.7(A) = 444VA. This is just the start. A PC like most power tools needs extra power to overcome inertia of the mechanics plus electrical values. Typically this is double the normal rating but for a short term only (about 1-2seconds), which the transformer needs to supply. You *can* overload a transformer, but the output voltage will sag, so much as not to get the PC to run and extra reserve is required. Since the transformer we are talking about is reasonably small, we can afford to go a little larger anyway. A good figure is 1.5 times the 444VA = 666VA. The closest commercially off the shelf transformers this size is 1000VA.
Our specification for this transformer so far is :
220V primary (or input) , 120V secondary (or output) , 1000VA. (but that’s not the whole story).
The nature of electrical standards vary from country to country and state to state and to cover all possibilities for connecting a transformer is beyond this scope, but here a few pointers.
Most domestic power is protected by RCD (residual current devices) which are designed to protect you from getting a shock. Connecting a transformer in the circuit will REMOVE this protection. Provided the appliance is double insulated (and the PC is) and you only use the transformer for the PC, you don't need an additional RCD. You would however need some kind of protection like a circuit breaker to protect the transformer's windings on the 120V side.
Article from IEEE (fianlly found it)
http://www.iee.org/Publish/WireRegs...supply_to_portable_and_handheld_equipment.pdf
Just because we are going down in voltage doesn’t mean the risk of shock is reduced any, don’t let this kid you, 120V can kill just as easily as 220V can.
To further limit dangers, the transformer can be bought with two lower voltages on the output, so the potential to ground is only 60V. This doesn’t add much to the price of the transformer and is a great safety mechanism.
So the specification for the transformer is now:
220V primary, 60V-0-60V secondary, 1000VA Double wound. <--New term. You might find auto transformers, don’t use these, since the large voltage step down will contravene many regulations, a double wound transformer is always acceptable.
If you follow mathematics you can see 60+60 = 120V so we still get 120V for the PC to work correctly. It’s a matter of how the transformer is connected to still get 120V.
Packaging and buying
The transformer needs to be fitted in box that protects you from getting zapped and for mechanical protection. A 1000VA transformer weighs around 15kg (30lbs) so it’s not the lightest of devices and needs a substantial case. If you want to take the transformer outside where you wash your car, then you can’t go without an RCD, on the output, remember.
Choosing from Brand x or Brand Y is not all that a criteria that’s important, it’s how the transformer is packaged so you can connect it to your house or workshop supply.
Rough prices in USD
1000VA transformer $250 (with a case)
RCD $80-$120
Shipping $40
Transformers that have a case already, plus the connectors so the PC can be plugged in. This is the safest option. How far is the transformer going to be from your car, do you need an extension cord, this would have to be purchased at the same time as the PC from the US. If you want to buy the parts yourself and put it all together, read on.
Connections and putting it all together
I recommend in all sincerity that you get a professional electrician to wire up the transformer since they are aware of local rules and regulations, and paying the extra is good insurance for your life. Although car detail enthusiasts can do miracles to paint finishes, let the professional take care of the power for the PC to make this happen!
50/60Hz
This rating means that the PC can run from a US 60Hz supply or a European 50Hz supply. The Hz (Hertz) is a speed issue…! At the start of this article, the OPM of the PC is rated at max 6000OPM. This figure is for 60Hz, for 50Hz, the speed is 5/6 the speed, that’s all you get, so the maximum OPM would be 6000 x 5/6 = 5000OPM. You can’t go any higher is speed and when speeds are mentioned in the forums about PC speed, for 50Hz, you have to multiply the setting by 6/5 for 50Hz users to obtain the same action speeds.
E.g. speed 4 on a US 60Hz supply would need to be 4.8 for a 50Hz supply. There are devices (frequency inverters) that change 50Hz to 60Hz, but the PC cannot be connected to them at all. You’re better off going to DC.
DC
Now we are talking a whole new ballgame. Not only do you need a transformer, but you also need a rectifier to go to DC, and totally different protection and this adds to the cost, significantly.
Lets start with what the PC (7424) needs, electrically:
Power
120 VAC, 50-60 HZ/120 VDC
Motor Amps : 3.7
No-load Speed
2,500-6,000 OPM
If you apply 220V to a 120V appliance it WILL be dead in a matter of seconds. We need to reduce the voltage from 220V to 120V and for this, we use a transformer. Like most things, size does matter, and we need to work out what type and size of transformer we need to run the PC. Too large and we need a forklift to move a transformer, too small and we run the risk of not starting the PC at all.
Transformers are rated in VA, (not WATTS) and lo, the figure is derived from multiplying the Voltage (the V bit) and the Amps (the A bit). So the PC needs 120(V) x 3.7(A) = 444VA. This is just the start. A PC like most power tools needs extra power to overcome inertia of the mechanics plus electrical values. Typically this is double the normal rating but for a short term only (about 1-2seconds), which the transformer needs to supply. You *can* overload a transformer, but the output voltage will sag, so much as not to get the PC to run and extra reserve is required. Since the transformer we are talking about is reasonably small, we can afford to go a little larger anyway. A good figure is 1.5 times the 444VA = 666VA. The closest commercially off the shelf transformers this size is 1000VA.
Our specification for this transformer so far is :
220V primary (or input) , 120V secondary (or output) , 1000VA. (but that’s not the whole story).
The nature of electrical standards vary from country to country and state to state and to cover all possibilities for connecting a transformer is beyond this scope, but here a few pointers.
Most domestic power is protected by RCD (residual current devices) which are designed to protect you from getting a shock. Connecting a transformer in the circuit will REMOVE this protection. Provided the appliance is double insulated (and the PC is) and you only use the transformer for the PC, you don't need an additional RCD. You would however need some kind of protection like a circuit breaker to protect the transformer's windings on the 120V side.
Article from IEEE (fianlly found it)
http://www.iee.org/Publish/WireRegs...supply_to_portable_and_handheld_equipment.pdf
Just because we are going down in voltage doesn’t mean the risk of shock is reduced any, don’t let this kid you, 120V can kill just as easily as 220V can.
To further limit dangers, the transformer can be bought with two lower voltages on the output, so the potential to ground is only 60V. This doesn’t add much to the price of the transformer and is a great safety mechanism.
So the specification for the transformer is now:
220V primary, 60V-0-60V secondary, 1000VA Double wound. <--New term. You might find auto transformers, don’t use these, since the large voltage step down will contravene many regulations, a double wound transformer is always acceptable.
If you follow mathematics you can see 60+60 = 120V so we still get 120V for the PC to work correctly. It’s a matter of how the transformer is connected to still get 120V.
Packaging and buying
The transformer needs to be fitted in box that protects you from getting zapped and for mechanical protection. A 1000VA transformer weighs around 15kg (30lbs) so it’s not the lightest of devices and needs a substantial case. If you want to take the transformer outside where you wash your car, then you can’t go without an RCD, on the output, remember.
Choosing from Brand x or Brand Y is not all that a criteria that’s important, it’s how the transformer is packaged so you can connect it to your house or workshop supply.
Rough prices in USD
1000VA transformer $250 (with a case)
RCD $80-$120
Shipping $40
Transformers that have a case already, plus the connectors so the PC can be plugged in. This is the safest option. How far is the transformer going to be from your car, do you need an extension cord, this would have to be purchased at the same time as the PC from the US. If you want to buy the parts yourself and put it all together, read on.
Connections and putting it all together
I recommend in all sincerity that you get a professional electrician to wire up the transformer since they are aware of local rules and regulations, and paying the extra is good insurance for your life. Although car detail enthusiasts can do miracles to paint finishes, let the professional take care of the power for the PC to make this happen!
50/60Hz
This rating means that the PC can run from a US 60Hz supply or a European 50Hz supply. The Hz (Hertz) is a speed issue…! At the start of this article, the OPM of the PC is rated at max 6000OPM. This figure is for 60Hz, for 50Hz, the speed is 5/6 the speed, that’s all you get, so the maximum OPM would be 6000 x 5/6 = 5000OPM. You can’t go any higher is speed and when speeds are mentioned in the forums about PC speed, for 50Hz, you have to multiply the setting by 6/5 for 50Hz users to obtain the same action speeds.
E.g. speed 4 on a US 60Hz supply would need to be 4.8 for a 50Hz supply. There are devices (frequency inverters) that change 50Hz to 60Hz, but the PC cannot be connected to them at all. You’re better off going to DC.
DC
Now we are talking a whole new ballgame. Not only do you need a transformer, but you also need a rectifier to go to DC, and totally different protection and this adds to the cost, significantly.