Frequency Conversion from 60 Hz to 400 Hz, using Horlick Motor-Generator Sets

Horlick motor-generator sets provide 60-400 Hz frequency conversion for naval and air force bases, missile and ground support operations, and manufacturers requiring 400 Hz power for product testing.

While the frequency of the power provided by utilities all throughout the world is either 50 Hz or 60 Hz, the frequency of the power used in the aircraft and aerospace industries is 400 Hz. This frequency has become the standard in these industries because transformers, motors, instruments and other equipment can all be made smaller and lighter when they run at 400 Hz. Since 400 Hz power is not transmitted by the utilities, there is a requirement for frequency conversion equipment that converts power from 60 Hz to 400 Hz. This 400 Hz power is used to power aircraft when the engines are turned off and it is also used by manufacturers in the aircraft and aerospace industries who require a 400 Hz power source to test their products.

The Horlick Company offers two varieties of motor-generator sets to convert frequency from 60 Hz to 400 Hz. The 400SC Model motor-generator consists of a 4-pole, 60 Hz, induction motor and a 24-pole, 400 Hz, synchronous generator mounted on a rigid steel base and mechanically connected via a flexible coupling. The base speed of the motor is 1800 RPM while the generator is 2000 RPM. In order to get the generator to produce 400 Hz power, the motor is driven by a variable frequency drive that raises its speed to 2000 RPM. The speed control in the basic 400SC Model design is open loop and as a result the generator output frequency is 400 Hz (+/- 1%). The frequency regulation can be improved to (+/-0.1%) by adding an encoder to the motor and switching the speed control to closed loop. 400SC Model motor-generator sets can be supplied in capacities that range from 12.5 KVA to 150 KVA. They can be used in military applications or most commonly by equipment manufacturers that require an economical power source that does not need to be precisely 400 Hz.

Horlick Motor Generators offer 60 Hz to 400 Hz Frequency Conversion

60 Hz to 400 Hz Frequency Conversion

The 400TR Model motor-generator is most commonly deployed in demanding military environments or in applications where a precise 400 Hz output is required. This motor-generator sets consist of a 6-pole, synchronous motor and a 40-pole, synchronous generator mounted on a common shaft. The machine rotates at a synchronous speed of 1200 RPM and it provides a precise source of 400 Hz power under the most adverse conditions. 400TR Model motor-generator sets are designed to run continuously for years with little or no maintenance. They can be supplied in capacities that range from 12.5 KVA to 375 KVA. They are frequently placed in custom weather-resistant enclosures and used in remote military applications all over the world.

Here are two recent examples of 400 Hz frequency conversion motor generator sets provided by The Horlick Company.

Product Testing for 400 Hz Heating and Air Ventilation System

A Pennsylvania based, engineering and manufacturing firm with customers in Defense, Aerospace, and Medical industries recently had a government contract to design and manufacture a custom heating and air ventilation system that was specified to run at 400 Hz. To be able to test their system prior to installation, a local source of 400 Hz power was required. Additionally, they had the requirement to test their product with variations to the output voltage and frequency.

To meet this requirement, the Horlick Company shipped a Model 400SC-203 motor-generator set that was rated for 25 KVA. In addition, Horlick modified their standard design to give the customer the ability to vary the generator output frequency from 360-440 Hz so that the customer could fully test their product per their customer’s specifications.

This system is currently operational and operating exactly as designed and specified. The customer described the Horlick Company as “great people to work with. Horlick accommodated our needed changes and enhancements, answered all of our questions and provided excellent communication throughout the process. We would be happy to work with Horlick in the future should the need arise.”

The Fourth 60 Hz to 400 Hz Motor Generator Shipped to the Letterkenny Army Depot

Horlick 400TR, 60-400 Hz, motor-generator sets are reserved for specialized military applications where a precise 400 Hz output is required. Recently the Horlick Company overhauled a 400TR Model motor-generator set for the Letterkenny Army Depot in Chambersburg, PA. This is the fourth such unit that Horlick has overhauled for Letterkenny. The unit overhauled is a Model 400TR-1003 rated for 125 KVA. The motor-generator set’s control system was enhanced to contain a programmable logic controller (PLC) and operator interface terminal (OIT) per the Depot’s specifications. The Horlick Company provided on-site startup and training for the custom control system.
The Letterkenny Army Depot is part of the U.S. Army Aviation and Missile Air Defense System command, and is known as the Army’s Capabilities Based Depot. Among the many capabilities provided by Letterkenny is the aviation ground power unit (AGPU) which is designed to provide electrical, hydraulic, and pneumatic servicing of rotary-wing aircraft. Horlick, 400TR Model, 60-400 Hz, frequency converting, motor-generator sets are an excellent choice for this Army Depot as they provide the precise source of 400 Hz power required for this demanding military application.

For more information on the Horlick Company’s 60-400 Hz line of frequency conversion motor-generator sets please contact us at 781-963-0090

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Horlick Company, Inc.
Call 781-963-0090 or

91 Pacella Park Drive
Randolph MA 02368
Phone 781-963-0090
Fax 781-986-1540