Have an emergency?

No problem. We are also available after business hours via our emergency cell phone. Contact us for any emergency service.

T +49 5066 90333-0
emergency(at)helmke.de

 

Highlights

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] ]

Diagnosis

We are at your service to carry out diagnostic procedures on your drives both in our workshops and on site.
Diagnostic procedures in our testing station: Any measurings and tests specified according to IEC EN-DIN and VDE regulations or according to customer specifications are available.


Standard tests for three-phase asynchronous squirrel cage and slipring motor:

  • Measurement of DC resistances of individual winding phases in stator and rotor winding
  • Insulation resistance check on stator winding
  • Insulation resistance check on rotor winding
  • Interface clarification of integration in higher process control instrumentation system
  • Stator winding check with high-voltage 
  • Rotor winding test with high-voltage (for new machines 2 x Un + 1,000)
  • No-load test: measurement of no-load current and no-load power at rated voltage and rated frequency
  • Short-circuit test: measurement of terminal voltage and power at rated current and rated frequency with locked rotor
  • Recording of no-load characteristic for evaluation of electro-magnetic dimensioning of the machine as well as determination of no-load losses (separation of friction and iron loss)
  • Recording of short-circuit characteristic, measurement of short-circuit loss
  • Measurement of rotor standstill voltage with stator under power at rated voltage and rated frequency (ratio check)
  • Check of rotating field and terminal marking
  • Measurement of shaft voltage on three-phase asynchronous motors
  • Evaluation of roller bearings according to SPM method
  • Measurement of vibration on A-side and B-side in 3 axes each, at idling at rated voltage and rated frequency
  • Functional test of accessories

Special tests:

  • Loss factor measurement (tangent delta) on inserted stator windings and individual coils
  • Determination of polarization index (PI-index)
  • Partial discharge measurement
  • Torque measuring at standstill
  • Noise level test
  • Core test on laminated core
  • Rod breakage test on three-phase squirrel cage motors
  • Testing and adjustment of neutral zone for commutator machines
  • Testing of tacho generators and incremental sensors
  • Interturn test at 1.2 x Un and
    1.2 x fN
  • Operational balancing
  • Check of air rate and velocity
    of flow in cooling circuit
  • Determination of magnetic
    center and axial play for side bearings
  • Vibration analysis
  • Rotation measuring on collectors and slip rings
  • Measuring of brush pressure
  • Whirling test (operation of machine at 1.2 times rated speed for a duration of 2 minutes, not possible on 60 Hz motors)
  • Thermographie

The following tests will be executed in order to evaluate the condition of
your drives:
  • Voltage
  • Ourrent
  • Output
  • Temperature
  • Speed
  • Vibration
  • Noise
  • Alignment
  • SPM Bearing Monitoring
  • Verification of inverter and PLC programming

With the available measurement equipment, these values can be documented
and consequences can be taken regarding condition of your motor.

 

Test of Coils and Windings

 

When manufacturing high-voltage and low-voltage windings, partly for converter applications as well as for traction motors, extended winding tests are becoming increasingly important in addition to the established quality inspections (e.g. determination of the insulation value, PI measurement and determination of the tangent-delta). The tests are necessary for all subsequent evaluations and preventive repair works. In particular, shock pulse and partial discharge measurements have emerged as important parameters over the past years.

In order to determine impulse voltage resistance, coil sections as well as entire stators are thoroughly tested at the HELMKE test facilities. The tests are feasible up to 40 kV using digital shock pulse test sources according to EN 60034 15 or IEE 522. These devices trigger a voltage rise within a very short time span (0.1 – 0.2 μs) which provides information on electric strength and insulation of the winding. Special analyzing and diagnostic equipment allow for the test to be carried out even on DC armatures via the so-called segment method.

 

Partial Discharge Measurements

Partial discharge measurings are carried out more and more frequently on running electric motors and generators worldwide. They help to identify insulation problems in an early stage and allow for more efficient planning of revision works. Partial discharges are a symptom of an ageing winding insulation which leads to small electrical sparks in the hollow spaces of the insulation. If the insulation system has faulty spots, the risk of a failure of the winding increases. Regular measurements of partial discharge activities provide relevant information in order to avoid a failure.

Partial discharges may not only occur in high voltage machines but, because of the pulse load, also in inverter-fed low voltage machines. A new partial discharge measuring system for motor-integrated inverters allows the measurement during active operation or during a winding test with impulse voltage.

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