PQ7 Motor-generator (MG) sets is designed to supply continuous clean power to sensitive loads e.g. computers, medical imaging devices, machinery, communications, controls and instruments and lights; to provided load isolation and electrical protection.
PQ7 MG also prevents load harmonics distortion and flicker from feeding back to the main switch board of the power system. It also prevent the incoming power disturbances e.g. SAG, DIP, Impulse, transient, Surges, Harmonic and Flicker, from traveling into the equipment’s final distribution board and eventually damaged the load/s. They can also perform frequency conversion.
PQ7 MGs offer many advantages over electronic systems.
With input of 50, output frequencies of 50, 60, or 400 Hz are available as standard. For custom designed systems, fixed frequency outputs from 25 Hz to 1200 Hz may be selected, or we can provide continuously variable frequency using a VFD on the motor. Power capacities range from 10 kVA to 20,000 kVA and up, depending upon system requirements.
PQ7 MG is designed to ride through the power network voltage DIP for 800mS or longer. No batteries or ultra-capacitor is required for uninterruptible power.
PQ7 MG come with a control panel which is usually unit-mounted, free-standing or wall-mounted. The panel will include the motor starter, output circuit breaker, metering, protective relaying, a voltage regulator and any other required components. Manual and automatic paralleling is also available.
Synchronous motor-generator sets
| Hz |
kVA |
Volts |
| 50-50 |
10KVA to 25MVA |
120 to 13,800 |
| 50-400 |
10KVA to 300KVA |
120 to 600 |
| 50-60 |
10KVA to 25KVA |
120 to 13,800 |
Additional motor-generator sets with controls
Variable frequency: 10KVA up to 25MVA
Ride thru: through the kVA range
Parallel control systems: through the kVA range
PQ7 Motor-Generator (MG) sets offer many advantages over electronic systems:
- Long life: 100,000 hours on the PQ7 MG set before major overhauls. Components are standard and available.
- Low maintenance cost: The equipment can be maintained by electricians and/or mechanics; no specialist is required. Also, on horizontal, single-shaft MG sets, there is no coupling, gear nor belt to wear out. Exciters are brushless; there are no commutators or brushes to replace.
- Low harmonic content on the input and output of the MG set from no load to full linear load.
- Low impedance for harmonics.
- High overload capability and a sustaining short circuit capability of 300% of nominal amps for 10 seconds.
- 1.0 power factor at the input without power factor correction.
- Simple, rugged construction for tolerance to voltage sags, spikes and noise, as well as complete isolation input to output.
- Gradual failure mechanisms (MG sets usually do not fail abruptly).
- Tolerance to heat, dust moisture and other environmental conditions.
- Built with the latest technology in building rotary MG sets
Electronic systems:
Electronic system have a life that would typically be shorter than the rotary MG set: The electronic components that are essential to the static converter become obsolete faster than those on a rotary MG set.
Electronic system will likely require an electrical expert for service: This expert will probably only be available from the manufacturer.
Electronics system have harmonics on the input and output: harmonic filters may have to be added on the input and output, and this is normally quite costly.
Electronic system are sensitive to voltage sags, spikes and noise and do not provide isolation input to output, which is obtained with an MG set.
Electronic system have electronic components that are sensitive to heat, dust and moisture.
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