Frequency Converters for Transformer Testing

1500 or 1800 RPM 50-50 Hz or 60-60 Hz: When no frequency conversion or adjustments are required. Often part of a multiple-output set in conjunction with a 150-Hz or 180-Hz generator.

No-Load Testing

Special Applications and Multiple Sets

90 to 400 Hz Induced Voltage Testing

For a more compact or economi-cal installation, it is common to combine a nominal-frequency generator and a high-frequency one with a common motor on the same base.

Kato also supplies specialty M-G sets for testing of other equipment at frequencies from 25-1200 Hz, single or multiple phases (depending upon ratings).

For no-load loss and heat run testing, these sets provide clean power with accurate regulation and voltage control. Several con-figurations are available:

These sets are used to energize the transformer at voltages exceeding its normal rating, in order to test its capability to withstand high voltages. They usually require low distortion and low partial discharge to permit detection of leakage in the tested transformer.

Configured to Your Needs

600 RPM 50-60 Hz or 60-50 Hz: When testing transformers at a rated frequency that is different from the local frequency.

Variable frequency: By using a variable-frequency drive and motor to power these sets, any output frequency in the 50 Hz to 60 Hz range may be selected. This set is most useful when either frequency may be used for testing.

MGG: For larger range requirements, like 50 to 180 or 50 to 200 Hz, it is most eco-nomical to use two generators, one 50 Hz to 60 Hz and the other 100 Hz to 200 Hz. These generators may be able to be driven by the same motor on a common shaft.

The generator can be designed to • operate with either leading or lagging power factor while remaining stable even at full output.

Frequency range/variable frequency: • Normal frequencies are 50 and 60 Hz for no-load tests, and either 150 or 180 Hz for induced-voltage tests. Smaller sets are available at 200 or 240 Hz, 300 or 360 Hz, and 400 Hz.

By using a variable-frequency drive • on the input, it is possible to build a set with wide frequency range such as 100-200 Hz, which may be advanta-geous for tuning the test system to a resonant frequency. A more than 2:1 frequency range is usually not eco-nomical, however.

Features & OptionsVoltage range: Kato is capable of • building motors or generators, with associated controls, to operate from 208V to 15 kV.

Associated with Emerson/US Motors • and Control Techniques: As part of Emerson Electric, Kato has access to design and manufacturing expertise in induction motors (U.S. Electrical Motors) and in variable-speed drives (Emerson Control Techniques). We also have a good working relationship with other drive and motor manu-facturers, so we can select the best solution for your needs.

Single-shaft sets: Smaller sets can be • built with the motor and generator on a single shaft supported by two bearings. Alignment is eliminated and vibration performance is improved. The system is also more compact and usually less expensive than sets with coupled shafts. Even on sets with more than two machines, the same principle can be used to reduce size and simplify by putting pairs of ma-chines on a single shaft and coupling these to the rest of the M-G.

Power range: Our smallest sets are • generally in the range of 25 kVA out-put. On the high end, we can manu-facture 50-60 Hz generators as large as 15 mVA (if you need larger, they can be paralleled), and 120-180 Hz generators as large as 5 MVA.

Kato builds synchronous motors as • large as 14,000 HP (with pony-motor starting), and induction up to 2000 HP. For larger induction motors we can call on the resources of Emerson motor facilities.

For best results where low PD is re-• quired, output voltage should be kept to 5000V or below.

Quiet power with low distortion: By • careful design of windings, we can produce a generator with distortion as low as 1% THD line-to-line. Normal-ly the neutral on these machines is not connected, so third harmonic is virtu-ally zero for balanced load. By using the optimum pitch, fifth and seventh harmonics may be substantially eliminated, and judicious use of skew reduces higher harmonics including slot harmonics.

Kato’s high-voltage form-wound • VPI insulation system reduces partial discharge noise on larger generators and permits higher output voltages than are available with random wind-ings, simplifying output transformer construction.

Rugged and reliable: The construction • of a motor-generator set inherently isolates the generator totally from the incoming mains. The generator and the equipment being tested is pro-tected from voltage sags, surges, or spikes that could cause damage.

The generator of the motor-generator • set is built to robust NEMA standards and shrugs off short-circuits and overloads.

Generous design and precision con-• struction allow Kato M-Gs to function trouble-free for decades with only occasional routine maintenance. Our customers have sets in daily use that were manufactured twenty years ago.

Kato provides service to all of its sets, • even those that would be considered ancient by the standards of the elec-tronics industry.

Advantages of MG Sets as Frequency Converters

Over twenty five years of experience: • Kato transformer test M-G sets have been operating reliably for twenty or more years. Our experience with 400 Hz aircraft power sets goes back even further.

Design capability for a tailored • performance: Kato Engineering has a fully-staffed engineering department located in North Mankato, Min-nesota. We will work directly with you to make sure that our design will perform the way you expect. Our engineers are accessible for technical questions from before the sale to post-commissioning.

Form coil winding capability: Kato • Engineering has a world-class mica-based high-voltage insulation system using 100% solids vacuum-pressure impregnation for void-free windings at voltages up to 15 kV. Not only does this system support long life and su-perior reliability, but by conservative design, partial-discharge noise from the windings can be minimized.

Controls expertise: In order to provide • a complete system, we maintain a staff of controls engineers dedicated to M-G set design, and an in-house switchgear manufacturing facility. We can supply complex controls incorpo-rating PLCs, touch-screen displays, and remote computer links.

A Company with Experience

Parts & ServiceWe at Kato Engineering know how important your power needs are. That is why we have experienced factory field service personnel on call 24 hours a day, every day of the year.

As well as repair and on-site rebuilding, we can assist you with the installation and startup and perform scheduled maintenance or training. We stock a variety of parts for quick delivery.

We provide technical manuals in electronic and hard-copy formats. These manuals include operation, maintenance and illustrated parts breakdown.

Our knowledgeable and friendly staff is always ready to answer your questions, send a needed component or arrange a site visit anywhere in the world.

Kato Engineering, Inc.P.O. Box 8447Mankato, MN 56002 USATelephone: 507-625-4011Fax: 507-345-2798Email: katoengineering@emerson.comWeb: www.kato-engineering.com

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