Custom development and manufacturing

About company
Our company profile is design, manufacture, maintenance service and repair of high-speed electric machines.

Custom development and manufacturing

WELMA high-speed reversible electric machine is designed to work as part of test stand equipment. WELMA is connected to the stand load unit and provides the load of the tested product according to the set program. WELMA is a synchronous electric machine with excitation from high-coercivity permanent magnets. This product is designed to operate both in motor mode converting electrical energy into mechanical energy of rotation and generator mode converting mechanical energy into electrical energy.

WELMA can operate in "starter-generator" mode. In starter mode the electric generator starts in motor mode for prespinning of the gas turbine engine. In this mode the frequency converter is powered from external power grid or by a high-voltage battery. When switching to generator mode, there is a switch to power from the electric generator and formation of electricity of a given type and quality at the output of the product.

The product is controlled from the operator panel on the control unit or via digital communication channel (RS-485 ModBus RTU).

WELMA can be customized considering your requirements with high degree of flexibility

  • By power: from 5 kW to 2.5 mW
  • By rpm: from 5 000 to 110 000 rpm

Also depending on the stand purpose and technical requirements various bearing supports can be used:

FGDB – foil gas dynamic bearings

HDB – hydrodynamic bearings

AMB – active magnetic bearing

BB – ball bearing (rolling bearing)

Comparison table for FGDB, HDB, AMB, BB with ceramic balls

Bearing type FGDB HDB AMB BB with ceramic balls
High-speed application 2∙106 DN 2∙106 DN 2.25∙106 DN <2∙106 DN
Application fields Energy / High-speed machinery/ Aircraft (ancillary equipment) Energy / High-speed machinery/ Aircraft (ancillary equipment) Vacuum systems / Mining and transportation of minerals / Machine-tool building / Medical equipment/ Energy / High-speed machinery/ Aircraft Energy / High-speed machinery/ Vehicles/ Aircraft
Sample application Electric motors for compressors, electric generator of micro gas turbine units with power up 300...400 kW; expanders-generators Electric motors for compressors, electric motors of vehicle drives; electric generator of micro gas turbine units; gas turbine and aircraft engines Electric motors for compressors, electric motors of turbomolecular pumps ; electric generator with power up to several MW; expanders-generators , starter-generator for flywheel energy storage system, gas turbine and aircraft engines, spindles Electric motors for compressors, electric motors of vehicle drives; electric generator of micro gas turbine units; expanders-generators, gas turbine and aircraft engines
Advantages Oil-free (no pollution); low sensitivity to temperature changes; low sensitivity to casing and rotor misalignments; ability to self-acting; low end losses, lower friction losses, mechanical leaks; low weight and costs High bearing capacity; efficient stabilization of high-speed rotor vibrations; high resistance to external vibrations; low weight; applicable for overcritical rotors Oil-free (no pollution); contactless; can operate in vacuum and at any speed - from zero to maximum; minimum breakaway torque; adjustable functional parameters; built-in sensors monitor rotor position with high accuracy; can be remotely controlled and monitored; applicable for overcritical rotors; high bearing capacity; low maintenance costs; low power consumption; ability to work at high temperatures (up to 540 ° C) Increased lifetime, higher heat resistance in comparison with metal balls; less sensitive to temperature changes inside the bearing and can maintain more accurate preload value; can operate at any speed- from zero to maximum; no high-frequency electric erosion of raceways; low weight; combination of radial and axial bearings
Disadvantages High dry friction torque during start-stop cycles; limited operating speed range from below due to the need for liftoff from zero; low bearing capacity and vibration resistance; not applicable for overcritical rotors Need for oil station; possible oil pollution; compact dimensions (diameters) for high rotational speeds; limited operating range of rotation speeds from below Big size and weight; high price; need for auxiliary supports; need for stand-alone backup unit; electronic control unit; additional power losses on AMB operation; additional parts in rotor design; control system complexity Possible need for oil station; possible oil pollution; limited speed range; compact dimensions (diameters) for high rotational speeds; need for precision manufacture and assembly of coaxial parts
Lubrication type Gas Fluid (oil) - Consistent / Oil
Stiffness, N·m 105...106 107...108 104...107, adjustable 108...109
Damping properties average high adjustable low, damping, to increase the need for elastic-damping supports

Cooling of WELMA products depending on your requirements and tasks can be:

  • air, liquid, combined.

The scope and composition of delivery can be different - ranging from the sale of WELMA product only (without power electronics set) to complete service including:

  • design of components and assemblies of the stand where WELMA is applied;
  • spare parts kit;
  • power electronics set with a frequency inverter;
  • REMOS automated remote monitoring system;
  • installation supervision of a unit or assembly;
  • product service and maintenance.
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