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04.06.2018 [ [more] ]

New Factory in SarstedtIn addition to the existing plant, a new state-of-the-art manufacturing facility is under construction at the HELMKE site in Sarstedt (near Hannover, Germany).[ [more] ]

Drive systems - engineered by HELMKEHELMKE is a worldwide acknowledged competence for the delivery of complete drive systems. The converter cabinets engineered by HELMKE are projected and manufactured for customized and branch-specific applications.[ [more] ]

Design and manufacturing of an electrical drive system

We were requested with the design and manufacturing of an electrical drive system for the adustable speed control of an NH3 screw compressor for the central refrigeration supply of an industrial chemical park.

Customer requirements:
  • High level of availability of the drive unit ≥ 8,000 h/ year
  • Installation of the inverter inside an air-conditioned concrete station
  • Motor designed as a water-cooled sleeve bearing machine
  • Outside installation of the motor / compressor unit
    (weather protection only through drip cover)
  • Planning has to take into account the occasional
    occurrence of NH3 at the installation site.
  • Power feeding for the drive through the customer’s 6 kV grid
  • Installation of the inverter transformer atop the roof of the concrete station
  • Provision for future extension with additional drive units

Reference Compressor
    • Development of a drive concept
    • Project design and manufacturing of the drive components
    • Compilation of an overview for the signal data exchange with higher-level controls
    • Factory testing of the drive unit under comparable load conditions
    • Delivery of the drive components and on-site assembly of the concrete station
    • Wiring of the power cables (transformer→ inverter)



    • HELMKE delivered a drive solution consisting of an inverter transformer and 12-pulse voltage source inverter for the speed control of a water-cooled induction motor.
    • At a constant counter torque progression of the operating machine the drive remains ‚subcritical‘ in a control range of 1,500 – 3,600 rpm.
    • In order to fulfill the customer’s requirements, a 04-pole motor, operated at 120 Hz stator frequency, was used.
    • The inverter was delivered in an air-conditioned concrete station. A notable feature is the automatic switch to air ventilation in case of malfunction in the air conditioning system to prevent overheating.
    • The drive system was put into operation in June 2006 and has been running to our customer’s full satisfaction ever since.

    Scope of Delivery

    Three phase squirrel cage motor

    • Type: DWK630-04
    • Power: 1,700 kW
    • Voltage: 660 V,
      120 Hz
    • Poles: 04-pole
    • M / P / C*: IM B3 / IP55 / IC81W

    Voltage Source Inverter

    • Type: NSFU S800-xx
    • Power: 1,700 kW

    Cast resintransformer

    • Type: DGH2,000 / 7,2
    • Power: 2,000 kVA
    • Voltage: 6,000 V


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