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Permanent Magnet Generators

Newton Derby is a main supplier of Permanent Magnet Generators (PMGs) to the major European manufacturers of large Synchronous Generators and Motors. These PMGs have been developed to provide excitation supplies for the exciter field systems of larger rotating machines that operate at continuous speeds of up to a maximum of 3600 rpm

Newton Derby prides itself on the quality of its design and development skills, enabling the company to offer special equipment for the most demanding applications, in addition to its established product range.

Newton Derby has produced permanent magnet generators for a variety of applications, including oil, gas, and hydro power. Our PMGs can be used as an independent supply, or as a brushless excitation supply for the field system of large rotating machines.  The magnets used on our PMGs can be either AlNiCo, or rare earth neodymium. Rare earth magnets are now our preferred choice, as they allow us to reduce the size of the PMG and are extremely resistant to demagnetisation in the event of a short circuit fault.

  • We have manufactured PMGs for large multinational companies, such as GE and ABB, as well as smaller companies in need of more bespoke solutions. All our PMGs are designed and manufactured based on customer needs, working to a specified power output, voltage, power factor, and speed, with a rating of S1 or S2 as required.
  • Our PMGs are impregnated using an epoxy resin. Class F insulation is used in all our PMGs as standard, which can withstand a temperature of 155°C, with higher temperature insulation available if necessary.
  • Our PMGs can be supplied either fully enclosed, or as a separate rotor and stator. Available mountings include foot, skirt, flange, or shaft mounted coupling and, in the case of a fully enclosed PMG, we will work to a desired IP rating.
  • All our PMGs undergo dynamic balancing, and both dynamic and static tests. Standard tests include open circuit and on load voltage checks, over speed, surge and flash testing, as well as insulation and winding resistance measures, with type tests available upon request.

PMG Stator/Rotor Unit

The Rotor is directly mounted on the shaft of the main generator or motor usually by means of a shrink-fit and key. The PMG stator housing is usually foot or flange mounted into the enclosure of the main machine.

Shaft-End Mounted PMGs (Tacho Style)

Directly mounted on the shaft end of the main generator or motor without the need for a flexible coupling or adaptor. The PMG stator housing is prevented from rotating by a flexible mount fixed to its underside.

Foot Mounted PMGs​

These can be supplied for the customer to mount on the base frame and couple to the parent machine.

Skirt Mounted PMGs​

Supplied for mounting onto the end of the parent machine via direct flexible coupling, these can be supplied to suit the customer’s own requirements.


Options and Benefits

  • PMG’s can be supplied as Stator/ Rotor units, or as fully enclosed auxiliary machines.
  • PMG’s are designed incorporating either Alnico or Rare Earth type magnets depending on the application and specifications.
  • Variety of mechanical forms dependent on the preferred method of mounting.
  • PMG’s can be used as a generator for renewable energy (wind or tidal).


  • Power Generation
  • Oil & Gas
  • Renewable Energy
  • Subsea
  • Military
  • Marine

Options and Benefits​

Newton Derby manufactures a large range of Permanent Magnet Generators in a variety of speeds and sizes to suit any application. Bespoke design solutions are our speciality.

Contact Us

Tel: 0113 255 5666
Fax: 0113 257 2206
Email: sales@newtonderby.co.uk