Rotating 50-60Hz frequency converters

Converter to test machines and work lines for companies producing equipment for 60Hz markets.

INTECH Automation Systems designs and manufactures 50 to 60Hz rotating frequency converters (motor-alternator assemblies) for heavy-duty testing, FAT, test benches and pre-shipment testing for export.

Output: 60Hz controlled, “true” sine wave, business continuity.
Delivery: engineering + board + control + documentation + support.

The converters built by Intech

INTECH Automazione Sistemi manufactures 50-60Hz frequency converter units in different power sizes, sized on actual operating conditions and loads applied during testing.

This allows us to select motor, alternator and control components according to measurable requirements: load profile, duty cycle, transients, service continuity, environmental conditions and maintenance criteria.

In practice, we size the system on actual testing: power, cues, load variations, and required power quality are translated into consistent design choices (electrical machinery, protections, control logic, sensors, and operator interface).

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Voltages selectable from our converters:

208 / 220 / 230 / 240 / 254 / 257 V and 380 / 400 / 415 / 440 / 460 / 480 V.

50Hz to 60Hz frequency variator with rotating assembly
50Hz to 60Hz frequency converters with rotating assembly
50Hz to 60Hz industrial frequency converter with rotating assembly
High-power 50Hz to 60Hz frequency converter for production and testing lines
ventilated cabin frequency converter
Frequency variator for production and testing lines from 50Hz to 60Hz
voltage and frequency converter control cabinet
voltage and frequency converter ventilated cabin
Frequency converter

Outdoor rotary converter with enclosure

Case history

  • Power supply: 400 Vac – 50 Hz
  • Motor: 850 kVA (SEVER)
  • Alternator output: 400 Vac – 60 Hz
  • Alternator: 630 kVA P.F. 0.8 (MARELLI)

Why a rotary converter is often the correct choice in “heavy-duty” testing

In industrial 60Hz testing, the criticality is not “getting 60Hz”: it is maintaining power stability and quality when the load is dynamic, intermittent, or introduces disturbances (typical of export lines and machines).

A rotary motor-alternator converter is often the correct choice when the test must cover “real-world” conditions, for example:

  • Rapid transients and frequent load changes (start/stop, machine cycles, nonstationary profiles)
  • Loads with high cues and repeated starts (motors, pumps, compressors, extruders, lines)
  • Need for a sinusoidal waveform and more “grid-like” behavior, useful for reliable and repeatable testing
  • Prolonged testing (FAT, endurance testing) where the priority is operational robustness and testbed continuity

INTECH Automazione Sistemi designs these systems for testing and test export, sizing the motor, alternator and switchboard according to the load profile, duty cycle and installation conditions (space, ventilation, possible soundproofing).

Check feasibility
Rotating frequency converter - spread of various types of frequency in the world
Rotating frequency converter - spread of various types of frequency in the world

Rotating vs Static: selection criteria for testing at 60Hz

There is no “absolute best”-there is the solution best suited to the testing profile and plant constraints. Below you will find practical criteria (those that matter on the shop floor and test stand).

Criterion Rotating (motor-alternator) Static (power electronics)
Load profile Very suitable for dynamic loads and heavy testing Excellent on more predictable profiles or with specific constraints
Cues and transients Robust management, good system inertia Depends on design margins and protection logic
Quality of the waveform Sine wave Depends on topology and filtering
Continuous duty/endurance test Typically suitable for long cycles Depends on cooling and sizing
Overall dimensions/noise Greater (manageable with cab) Minor
Maintenance Mechanical + electrical part Predominantly electronic

Frequency converter: what it is and what it is used for

Worldwide power generation and distribution has led to solutions that, although based on the same principles, differ from country to country, with systems at different voltage and frequency values.

Interchanges of power-powered industrial products between states, now even more intense under globalization, require machines to be adapted to the voltage and frequency values of the destination country. In fact, there are different networks and standards (e.g. 380V-50Hz, 400V-50Hz, 415V-50Hz, 440V-60Hz, 480V-60Hz, etc.) and this has made it necessary for manufacturers to produce and test machines intended for markets with electrical systems other than that of their own country.

A 50-60Hz frequency converter is a system that allows machines and plants designed for foreign markets (USA, Canada, parts of South America and other countries) to be powered at 60Hz from the European 50Hz grid.

In terms of export testing, it is mainly for:

  • Factory testing and FAT before shipment
  • Functional testing under electrical conditions consistent with the country of destination
  • Test benches and R&D laboratories requiring 60Hz power supply for testing with selectable voltages

Selectable voltages, the important value for exporters

On systems with PLCs and HMIs, typical 60Hz voltages can be arranged, for example:
208 / 220 / 230 / 240 / 254 / 257 V and 380 / 400 / 415 / 440 / 460 / 480 V.

Technological development has made it possible to devise and produce different methods for energy conversion at different voltages and frequencies.

Technical insights

Conversion methods: most common solutions

An endothermic engine (combustion, diesel, fuel injection, etc.) is mechanically coupled to an alternator designed to achieve the required voltage and frequency. These units are normally applied where there is no possibility of an electrical source.

Electric motor and generator are mechanically coupled; the motor, connected to the national grid, provides mechanical power to the generator. To achieve, for example, a 50Hz to 60Hz conversion, a speed multiplier must be interposed between the motor and generator.

This solution, sometimes thought to be “obsolete,” is actually more common than one might think: it is clearly observed in various industrial settings where the system’s load profile and disturbances make particularly robust testing criteria necessary.

There is no rotating organ: power generation at different voltages and frequencies is achieved with modular semiconductor components. Powered by the commercial grid, they are driven by PWM microprocessor technology to deliver power with varying voltages and frequencies.

The use of static units has seen exponential growth in versatility, stability, maintenance-free operation, and quiet operation. However, they require a power source and are not applicable everywhere.

Method Note: The choice among these possibilities always depends on the needs and characteristics of the load (the machines) to which the generator is to supply power.

Technical requirements motivating the rotating choice

The guarantee of good testing for equipment intended to operate at a frequency different from the commercial grid is achieved by providing a supply with a perfectly sinusoidal voltage waveform at the same frequency as that of the grid in the country of destination.
Any disturbance on the supply voltage of the motor supplying mechanical power to the generator does not significantly alter the shape of the voltage generated at the output. The possible addition of a flywheel between the two machines mitigates speed deviations, and the stored energy can make up for minor interruptions in the commercial grid.

The near-perpendicularity of the final stretch of the torque-speed characteristic of modern asynchronous motors offers a guarantee of stability of the frequency of the voltage produced by the generator, because the load point has very little variation at different loads.

The low output impedance and sinusoidal shape of the voltage generated by an alternator are not achievable in the same way from a static unit: even with output L-C filters, the PWM “construction” of the sine wave can contain minimal high-frequency notches. Associated with a generally higher output impedance than a generator, these can result in waveform distortions when the load is distorting or emitting noise on the power source.

All about Rotary Frequency Converters

When the Customer’s request is oriented toward a rotary converter, INTECH Automation Systems, in addition to supply, installation and maintenance of electrical machines, integrates solutions that significantly improve some less favorable aspects of the traditional rotary system.

For motor starting, we introduce a variable frequency inverter that brings the unit up to speed smoothly, without spikes in absorption from the commercial grid.

With a motor equipped with an encoder, speed accuracy and thus a strictly constant frequency is achieved by the inverter.

The power factor of the inverter is practically unity. Through the inverter, it is simultaneously possible to improve the reduced cosφ of the motor during periods of reduced load operation by reducing the voltage to the motor to maintain the rotating field and thus the rotation of the unit: in effect, a partial power factor correction is implemented.

The inverter system lends itself to an extension of the total installed power when it is necessary to parallel the alternator of the “base” unit with another new or existing unit (equipped with direct or star-delta starter). Paralleling requires concurrence of voltage, frequency and phase between the two groups: the presence of the inverter, thanks to the speed variation, allows the search for electrical synchronism and phase coupling between the machines.

A further development is to equip the application with a supervisory system to monitor operating conditions in real time and ensure safe response to calls for service from the group.
This feature also promotes remote control: in addition to correct power delivery, it enables checks on winding and bearing temperatures, vibration, ventilation efficiency, etc. The system can also connect to the Customer’s management system to monitor duty cycles, optimize operating conditions and determine operating costs.

The rotating assembly has no significant noise pollution; however, placement in a soundproofed and ventilated cabin can reduce the residual audible noise to zero, allowing the assembly to be placed side by side with nearby offices or businesses. Forced ventilation ensures that no dust particles or granules that could damage moving parts enter the cabin.

Coupled electric motor and generator: why they are a qualitatively better solution in some tests

In some applications, frequency converters consisting of a coupled electric motor and generator may be qualitatively better performers. For this reason, the use of rotating electric machines deserves to be evaluated when testing must be reliable even under complex industrial conditions.

In the daily use of companies that have to test products for the foreign market, it often happens that the systems under test introduce disturbances in their power source (alterations, distortions, harmonics). In such cases, it becomes useful to have a power source that offers a high guarantee of test quality.

Frequency converter

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