Every machine American Plant and Equipment lists for the United States market is stated as running on 480V, 60Hz, three phase, because that is the supply most US industrial plants actually have. Machines built to a different electrical standard can almost always be made to run here, but “almost always” hides a list of decisions worth making before the machine is on a truck.
Two things change at once, and they are not the same problem.
Voltage is the easy half
A transformer solves voltage. Size it for the machine’s full load current with headroom, get the winding configuration right for the grounding arrangement your plant uses, and remember that the transformer needs somewhere to live, needs its own protection, and adds losses you will pay for every hour the line runs.
What catches people out is that a machine rarely has one voltage. The main drives may be one, the control circuit another, the heaters a third, and the panel lighting a fourth. Get the full list from the electrical schematic before you size anything.
Frequency is the half that changes the machine
Going from 50Hz to 60Hz changes what the machine does, not just what it draws.
- Induction motors run about 20 percent faster. Line speeds, roll surface speeds, pump and fan outputs and gearbox ratios all move with them. Sometimes that is welcome capacity. Sometimes it is a product that no longer forms correctly, and the answer is a sprocket, a pulley or a gearbox change.
- Fans and pumps follow the affinity laws. Twenty percent more speed is roughly seventy percent more shaft power. A motor that was comfortable at 50Hz can be overloaded at 60Hz doing the same job.
- Motors themselves need checking. Many industrial motors are dual rated and simply need reconnecting. Many are not. The nameplate is the first thing to photograph.
- Variable frequency drives change the conversation. Where a machine already runs on drives, the frequency question often becomes a parameter change rather than a mechanical one, provided the drive’s input voltage rating suits the new supply.
- Timing that was derived from the mains moves with it. Older control gear, and anything with a synchronous timing element, will run fast.
The parts people forget
- Heaters. Resistive heaters do not care about frequency, but they care a great deal about voltage. Power scales with the square of the voltage, so an unconverted heater is either a fire risk or a machine that never reaches temperature.
- Control transformers and power supplies. Cheap to convert, easy to overlook, and the machine will not start without them.
- Safety circuits. Interlocks, light curtains, emergency stop relays and guard switches all need to work at the new control voltage, and they need to still satisfy the standards your plant is inspected against.
- Labelling and documentation. Panel legends, wiring numbers and the schematic itself should reflect what the machine has become. The next person to work on it will believe what is written on the door.
Do the work before it ships, where you can
It is far cheaper to convert a machine while it is still accessible than after it has been rigged into place. Our reconditioning shop has mechanical, electrical and electronic technicians who rebuild, disassemble, reassemble, pack and ship machinery, and doing the electrical work as part of that process avoids a second mobilisation and a second set of surprises.
Before you commit
Ask the seller for the full electrical schematic, the motor nameplates and the control panel photographs at the enquiry stage rather than after the purchase order. If you would like somebody to read them with you, that is exactly the kind of question a consulting session is for, and our team is always reachable through the contact page.