Rotary frequency converters (motor-generator sets) 5–20 MVA up to 13.8 kV
Rotary frequency converters rated from 5 to 20 MVA for voltages up to 13.8 kV, assembled from a motor and a generator. The sets supply test fields that need practically sinusoidal voltage without the harmonics of electronic converters. Voltage and frequency are regulated independently of each other over the whole operating range.
- Output
- 5–20 MVA
- Voltage
- up to 13.8 kV
- Frequency conversion
- 50/50, 50/60, 60/60 Hz (by different numbers of poles)
- Degree of protection
- IP20 – IP55, IP56
Price, availability and lead time on request. We help with analogue selection, customs clearance and delivery.
Description
The set consists of a motor and a generator, which can be induction or synchronous machines or a combination of them. If machines with different numbers of poles are chosen, the set converts both voltage and frequency (50/50, 50/60 or 60/60 Hz). Unlike a transformer, the motor and generator are linked only mechanically, through the shaft, and there is no magnetic coupling between them. Therefore there is no direct electrical connection between the supply grid and the test field, and the set provides galvanic isolation and filters grid disturbances. For the test stand this means that processes during tests do not pass directly into the supply grid, and grid disturbances do not reach the test object.
The voltage and current waveform at the output is practically sinusoidal. On motors and transformers that are fed from converters in service, reference measurements can be made without additional losses from the harmonics of electronic converters. The sets have high overload capacity and short-circuit withstand, which is no less important for a test field. Degrees of protection range from IP20 to IP55 and IP56, cooling is by air or water, power factor is from 0 to 1, and speed depends on the application and frequency.
On request the scope of supply includes a frequency converter cabinet with switchgear, a squirrel-cage motor, a synchronous generator, auxiliary drives, an input transformer, a lubrication system, a coupling and other components. The set is supplied mounted on a common frame or as separate machines, and the manufacturer gives recommendations on cables and installation. Machine sets for test fields and special applications are built up to frame size 800. The output, voltage, frequency range and cooling system of the set are chosen according to the technical specification of the particular test field.
An example of supply is a set for testing extra-high-voltage power transformers at the largest transformer plant in the Middle East. It included a synchronous generator of 8 MVA, 6 kV, 50–100 Hz with a harmonic factor of less than 0.5% against a specification requirement of not more than 3%, a 2500 kW induction motor, a frequency converter, a coupling, a lubrication system, measuring transformers and an excitation control device on a vibration-isolated frame. The set passed a 24-hour trial run under load in Berlin. Such machines are installed at factory test stations of transformer and electrical machine plants.
Technical specifications
| Output | 5–20 MVA |
|---|---|
| Voltage | up to 13.8 kV |
| Frequency conversion | 50/50, 50/60, 60/60 Hz (by different numbers of poles) |
| Degree of protection | IP20 – IP55, IP56 |
| Cooling | air or water |
| Power factor | 0–1 |
| Scope | frequency converter with switchgear, squirrel-cage motor, synchronous generator, auxiliary drives, input transformer, lubrication system, coupling |
| Example | 8 MVA / 6 kV set, 50–100 Hz, with a 2500 kW motor |
Request a price and lead time
Rotary frequency converters (motor-generator sets) 5–20 MVA up to 13.8 kV. We reply within one business day.
Or email sales@usk.ua or call 044 339-50-20.
Questions and answers
What frequencies can be obtained at the output of the set?
Depending on the combination of machines with different numbers of poles, the set works in the 50/50, 50/60 or 60/60 Hz modes. In the completed project the 8 MVA generator delivered 50–100 Hz.
Why does a test field need a rotary converter instead of an electronic converter?
The voltage and current waveform is practically sinusoidal, so reference measurements on motors and transformers are made without additional losses from harmonics. In the completed project the harmonic factor was less than 0.5%.
What output and voltage do the sets have?
Output from 5 to 20 MVA, voltage up to 13.8 kV, power factor from 0 to 1. Cooling is by air or water.
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