Single Phase Frequency Converters 50/60 Hz
18 models 1KVA to 20KVA
50 or 60hz input,
50hz or 60hz output
Single Phase Frequency Converters 400hz
18 models 1KVA to 20KVA
50hz or 60hz input and
400hz output
Three Phase Solid State Frequency Converters
50 or 60 Hz
57 models 10 to 320KVA
Three Phase Solid State Frequency Converters
57 models 10 to 320KVA
Solid State Design Considerations Manuals and Connection Diagrams Accessories
Outdoor Enclosures, Carts,
Distribution Panels etc.
Notes and Photos
Rotary 1 or 3 Phase Frequency Converters
50 or 60hz output
6KVA to 2000KVA
Rotary 400Hz output Frequency Converters
1 or 3phase
10KVA to 250 KVA
Rotary Frequency Converters Accessories
Enclosures (Indoor quietized and Outdoor) Digital Meters, RS232 and Data Logging, etc.
Rotary Design Considerations Starting Surge of motors in the load, Large SCR loads, power factor and resistive loads, Operating Noise Level.
Rotary Application Notes and Photos Operating Noise and solutions to this problem Line Isolation Sets
  Visicomm Industries
Solid State Frequency Converter Rotary Frequency Converter

Electrocon Frequency Converters

60 to 50 Hz · 50 to 60 Hz · 60 to 60 Hz Isolation · 50/60 to 400 Hz

Rotary Construction



Rotary Application Notes and Photos
60 to 50 Hz-- Testing Prouducts for export to 50 Hz countries
  Operating 50 Hz Machines from 60 Hz U.S. utility power.
Importing a machine or an entire factory
50 Hz to 60 Hz-- Operating 60 Hz machines in a 50 Hz country.
Moving a machine or an entire factory
  Used in 50Hz countries to test products to be exported to the USA
50 or 60 Hz to 400 Hz -- Aerospace applications

Rotary Design Considerations (Click Here)
Motor Starting Surge, Audible Operating Sound Level,
Vertical vs. Horizontal Construction

Rotary Accessories (Click Here)
Digital Output Meter Package, RS485 Data Log for Export
Testing, Enclosures (Outdoor and Indoor Quietizing),
Containerization, distribution Panels



A brushless Motor and a brushless generator are mounted side-by-side (vertical one atop another to minimize footprint is an option) on a welded steel frame skid. This design (as opposed to solid state full sine wave design) is recommended because of:

  1. Rotary Design is inherently less expensive for 3 phase units 12KVA or larger. A similarly rated unit would be about 50% higher in price and, because of the comparatively limited motor starting capability of solid state designs, a unit with the same motor starting surge rating would be about twice as expensive.
  2. Rotary Design is easier to repair in the field and has far fewer components that are subject to failure and subsequent search for replacements that are no longer made. Any fair sized city worldwide has a motor repair shop capable of repairing rotary units and electric motors are commonly many years old before the repair shops see them. Should the occasion ever arise, we have our own list of authorized repair shops and 1 or 2 day turnaround is the rule. Many rotary frequency converters still running in the field are 25 years old or more.
  3. Rotary Design is more rugged and flexible in the loads it can handle aside from greater motor starting surge capacity. For example, SCR loads and welders are almost insurmountable problems when using a solid state approach.


  • Brushless induction motor--low slip, high efficiency, 1.15 service factor
  • 3 phase only for 12KVA and larger sets. For sets 12KVA and over. input any 3phase voltage. Medium voltage (3300V, 4160V. and up for sets over 500KVA)
  • Speed 1000 to 1800RPM up to 1000KVA, 600RPM over 1000KVA


  • Brushless synchronous generator, 1000 to 1800RPM ( 600RPM optional over
  • Voltage 90V. to 575V., 1 or 3 phase, 12 wire reconnectable, medium voltage also available
  • Solid State automatic voltage regulator holds voltage constant within +/- 0.5% from no load to full load. Voltage setting adjustable by potentiometer mounted on control panel door +/- 10% of nominal voltage.
  • 15 models from 5KVA to 156KVA and 14 models from 156KVA to 2000KVA

Control Panel

Unit mounted (on the same skid above the MG set) or for remote panel installations, wall mounted or free standing - see discussion of operation noise below. The control panel consists of a NEMA 12 electrical enclosure containing a motor starting assembly with overloads (wye-delta reduced voltage for motors 50HP and up) stop-start push buttons, motor on light - generator output voltmeter, ammeter, frequency meter (with phase selector switch for 3 ph), 0.5% automatic voltage regulator with panel door mounted voltage adjustment potentiometer and molded case output circuit breaker. With unit mounted controls, the installer has only to connect the input power to the control panel - the output power is then available at the circuit breaker terminals.

Audible Noise:

Rotary units above 30KVA may exceed 83dBa at 3 ft. and, if people are nearby, that may present a problem. There are three approaches to solving the problem listed in order of cost (lowest first):

  1. The control panel may be specified as separate (not mounted on the skid) and the controls located near the operators with the unit located in another room with other "noisy" equipment. No additional charge.
  2. Sound attenuating buffer to bring sound down to below 83dBa at 3ft. Reasonable added cost.
  3. Specify an optional (extra cost) ventilated sound attenuating indoor cabinet enclosure - with a sound level of 73 dBa at 3ft. maximum.

Want to know what a given dBa level sounds like? Click here

Typical Open Horizontal Construction
6.25 to 25KVA


Note: Control Panel mounted and prewired on same skid as rotary components requires only bringing utility power into control panel to result in output power available on output load contacts of the circuit breaker inside the panel

  • Typical dimensions: 40 to 45" Wide X 25 to 28" Deep X 35" High
  • Weight: 550 to 1000 lbs.

Operating dBa 76 to 78 @ 3 ft. is not objectionable in most industrial environments. In lab environments, the generator set can be stationed in an equipment room while the control panel - with all the start-stop controls, meters, voltage adjustment and output circuit breaker terminals - is wall mounted in the lab itself. In extreme cases, ventilated sound attenuating enclosures are available.

Typical Open Horizontal Construction
30 to 125KVA

40 KVA with Control Panel seperately mounted to isolate rotary components for noise control 100KVA with skid mounted control panel 100KVA Control panel - Door open to show output circuit breaker and WYE-DELTA motor starter.

For dimensions and weights, call or fax the factory.
Options available at extra cost include: Outdoor Enclosure with anti-condensation motor and generator coil heaters. Control Panel outdoors in the enclosure or mounted indoors.
Open Vertical Construction - to minimize footprint

  1. Quietized Vertical Construction - see below, Enclosed Quietized Vertical Construction.
  2. Synchronous Motor - for +/- 0Hz operation

Typical Open Horizontal Construction
156 to 375KVA


Units of this size require special baffling to meet OSHA requirements. Shown here is the 313KVA unit with sound baffles (83dBa @ 3ft.). Without baffling the noise level is 97dBa. Cost can be reduced with remote panel location at no extra charge.

Options available include:

Quietized Vertical Enclosed Construction - less than 75dBa at 3ft.

Typical Open Horizontal Construction
- Gearbox Type 400 to 2000KVA

Optional Sound Reducing Enclosure

Pictured is a 62.5KVA unit enclosed in an 14ga. enameled steel, ventilated enclosure with sound attenuating foam

Quietized Cabinet

A list of various countries and the standard 1ph / 3ph voltages and frequencies for each.

Introduction (Click Here)
Countries A - F (Click Here)
Countries G - M (Click Here)
Countries N - Z (Click Here)

Typical Construction
Questions? Click here to contact us