Short answer: industrial machines in Korea are built for 380V 60Hz three-phase power. In a 60Hz country they need a transformer at most. In a 50Hz country a transformer alone is not enough for motors connected straight to the line: on a 400V 50Hz supply a 380V 60Hz motor carries about 26% more magnetic flux than it was designed for and turns about 17% slower, so the machine needs drives, a lower voltage, different motors or a frequency converter.
This guide is for importers and dealers looking at a used or new machine in Korea. It covers what the Korean supply is, how your supply compares, what happens to each part of the machine, and what to ask for before you pay.
What 380V 60Hz means on a Korean machine
Korean factories are supplied with three-phase power at 380V between phases and 220V from phase to neutral, at 60Hz. A drive maker’s 2026 country factsheet lists the Korean mains as 3-phase 380V (440V) with a 10% tolerance at 60Hz, which matches what you will see on most nameplates. Some sites also run 220V or 440V three-phase equipment, so the nameplate on the actual machine decides, not the country.
How your supply compares with 380V 60Hz
| Your three-phase supply | Examples (nominal values) | What a Korean 380V 60Hz machine needs |
|---|---|---|
| 380V, 60Hz | Parts of Brazil (220V or 380V) | Usually nothing. Confirm which voltage your site has. |
| 400V, 60Hz | Saudi Arabia, Philippines | The voltage is about 5% higher. That is inside the tolerance of most equipment, but check the nameplate tolerance and the transformer taps. |
| 440V to 480V, 60Hz | United States, Canada, Mexico | A step-down transformer to 380V. Frequency already matches. |
| 220V, 60Hz | Peru, Taiwan, parts of Colombia | A step-up transformer to 380V. Frequency already matches. |
| 400V, 50Hz | EU countries, United Kingdom, Vietnam, Indonesia, Thailand, India, China, Turkey, UAE, Egypt, South Africa, Uzbekistan, Kazakhstan | Both voltage and frequency differ. Use one of the four conversion methods below. |
| 415V, 50Hz | Nigeria, Kenya; often found in practice in Malaysia and Australia | Same as above, with a slightly larger voltage gap. |
Why frequency matters more than voltage
The magnetic flux in an induction motor depends on voltage divided by frequency. A 380V 60Hz motor is designed for 380 / 60 = 6.3 volts per hertz. Connect it to 400V 50Hz and it gets 400 / 50 = 8.0 volts per hertz, about 26% more. The iron core saturates, the motor draws a much higher magnetising current and it overheats, even with no load.
To keep the flux right at 50Hz the voltage has to fall in the same proportion: 380 x 50 / 60 = about 317V. Speed falls too. A four-pole motor has a synchronous speed of 1,800 rpm at 60Hz and 1,500 rpm at 50Hz, so pumps, fans and conveyors driven directly from the line deliver about 17% less.
What happens to each part of the machine on 50Hz
Most articles on this question stop at the motor. A production machine has several other parts that react differently, and they decide how much the conversion costs.
| Part | Effect of a 50Hz supply | What to check |
|---|---|---|
| Motors connected straight to the line (hydraulic pump, coolant pump, fans, conveyors) | Overheat at full voltage; run 17% slower at reduced voltage | Motor nameplates. Some motors are dual rated for 50Hz and 60Hz. |
| Motors behind a drive (CNC spindles and axes, servo motors, inverter-driven pumps) | Not affected by supply frequency, because the drive creates its own output frequency | Input voltage range and frequency on the drive nameplate. Many drives accept 50Hz and 60Hz, but some are fed through a transformer inside the machine. |
| Fixed-displacement hydraulic pumps (many hydraulic injection molding machines and presses) | Oil flow falls with motor speed, so cycle times get longer | Whether the lower output is acceptable or the pump motor needs a drive |
| Control transformer and other internal transformers | A transformer designed for 60Hz runs hotter on 50Hz unless its input voltage is reduced in proportion | Frequency rating and available taps |
| Contactors, relays and solenoid valves with AC coils | Coils rated only for 60Hz draw more current on 50Hz | Coil ratings. Many are marked 50/60Hz. DC coils are not affected. |
| Heaters (barrel heaters, ovens, sealing bars) | Frequency makes no difference. Power changes with the square of voltage: 400V on a 380V heater gives about 11% more heat | Temperature controller settings and wiring ratings |
| Chillers, compressors and air conditioners on the machine | Capacity falls with speed | Maker’s statement on 50Hz use |
Four ways to run a 380V 60Hz machine on a 50Hz supply
- Reduce the voltage with a transformer. A transformer from your supply down to about 317V keeps the volts-per-hertz ratio correct for the whole machine. Everything line-driven runs 17% slower, and the transformer has to be wound for that ratio. This suits machines where lower output is acceptable.
- Put a variable frequency drive on each line-fed motor. The drive takes your 400V 50Hz supply and is set to the motor nameplate values, 380V at 60Hz, so the motor returns to its original speed. The control circuit and any transformers still need their own check.
- Replace the motors. Fit motors wound for your supply. Because a 50Hz motor of the same pole count is slower, pump sizes or pulley ratios may have to change to keep the original output.
- Feed the whole machine from a frequency converter. A static or rotary converter turns your supply into 380V 60Hz, so nothing on the machine changes. The converter has to be sized for the full machine load, which makes this more practical for small machines than for large ones.
A transformer never changes frequency. If a seller says a transformer is all you need, ask which of the methods above they mean.
What to ask for before you buy
- A clear photo of the main nameplate: voltage, frequency, phases, total kVA or full-load current.
- Photos of every motor nameplate and every drive nameplate.
- The electrical drawings, if the seller still has them, and the control circuit voltage.
- The tap list of the machine’s own transformer, if it has one.
- A list of chillers, compressors and other auxiliary units that ship with the machine.
Give these to an industrial electrician in your country before you pay. The conversion cost belongs in your comparison with a machine built for your supply.
Points to watch
- Do not judge by the country alone. Sites within one country can have different supplies. Measure or ask your utility.
- Electrical safety and conformity rules are separate from whether the machine runs. Some countries require conformity marking, registration or inspection for imported machinery, including used machinery. Confirm with your customs broker or local customs office before importing.
- Modifications change the machine. Have the work done and documented by a qualified electrician, and keep the original nameplate data.
Frequently asked questions
Can I connect a 380V 60Hz machine directly to 400V 50Hz?
Not if it has motors or transformers connected straight to the line. They would receive about 26% more volts per hertz than designed and overheat. Parts fed through drives may accept the supply, but each drive nameplate has to confirm it.
Can a transformer convert 50Hz to 60Hz?
No. A transformer changes voltage only. Frequency is changed by a variable frequency drive on a motor or by a frequency converter for the whole machine.
Is a Korean 380V 60Hz machine a good fit for 60Hz countries?
Yes, this is the simple case. The frequency already matches, so the machine needs a transformer only where the voltage differs, for example 480V in the United States or 220V in Peru.
Are CNC machines affected less than hydraulic machines?
Usually. Spindles and axes on a CNC machine run from drives, which do not depend on supply frequency. The coolant pump, hydraulic unit, chip conveyor and internal transformer still need checking. A hydraulic press or injection molding machine with a line-fed pump motor is affected directly.
Who carries out the conversion?
Normally an electrician at the destination, after the machine arrives. When you buy through us we send nameplate photos and the electrical drawings the seller has before you pay, so the work can be planned in advance.
Buying a machine from Korea
HANA for U, a trading company based near Incheon, buys machines from Korean factories and manufacturers that do not export themselves, then inspects, packs and ships them. See used machinery from Korea for brands, inspection points and shipping, or the Korea export sourcing overview for everything we handle.
Request a quote: send the machine type, model, year range and your country and site supply through the quote request form, by email to ohytto@naver.com, or on WhatsApp. Prices and terms are stated on each quote.
Sources
- Lenze, Ecodesign Factsheet South Korea 2026: Korean mains voltage and frequency. Checked 5 October 2026.
- World Standards, three-phase electric power by country: nominal three-phase voltage and frequency. Checked 5 October 2026.
- Industrial Monitor Direct, 60Hz motor on 50Hz supply: the volts-per-hertz rule for motors. Checked 5 October 2026.
