TMDS Tests & Procedures

The tests and procedures performed by the TMDS are described below.  Listed under each test are the parameters monitored and recorded by the TMDS computer during the test.  These parameters are recorded at set intervals during the test. Note that the term “commutator end” is used to define the end of the motor opposite the pinion end (or drive end) although this term is not accurate for AC motors.

The TMDS computer monitors the motor's test parameters hundreds of times each second during a test. If the computer detects a problem, the test is aborted and the test voltage is removed from the motor.   The computer's constant monitoring, as well the safeguards built into the hardware, result in an extremely safe system for both the operator and the motor under test.  All tests can be performed in both rotational directions.

Static Tests

Hipot
The Hipot test is performed by applying a very high AC voltage between the motor’s windings and the case of the motor.  
    
   
Voltage
   
Amperage

Insulation Resistance
The Insulation Resistance test, also known as a Megger test, is performed by applying a very high DC voltage between the motor’s windings and the case of the motor and taking a resistance reading.

   Voltage
   Resistance

Winding Resistance
The Winding Resistance test is usually performed only on AC motors.  This test is performed by applying DC voltage to the motor leads and taking a resistance reading.   

    Voltage
   
Resistance

Field Winding Impedance (Separately wound DC motors only)
During the impedance test, a pre-determined AC voltage is applied to the motor's field winding.

    Voltage
   
Amperage

Dynamic Tests

Brush Seating and Air Curing (DC motors only)
During the brush seating and air curing procedure, the motor is rotated with three different voltages applied to the motor.  The operator then seats the brushes and air cures the commutator during the different voltage levels.  The operator signals his readiness to proceed to the next voltage level by pressing a button which alerts the control computer to proceed to the next voltage level. 

Full load
During the full load test, voltage is applied to a DC motor until a predetermined rotational speed is achieved. In the case of an AC motor, the frequency of the power applied is adjusted until the desired speed is achieved. A dynamometer applies a predetermined amount of torque.

   Voltages
  
Amperages

  
Frequency (AC motor)
   D
irection of rotation

  
Motor speed

  
Torque
   Efficiency
  
Ambient temperature
   Commutator bearing temperature

  
Pinion bearing temperature

  
Frame temperature
   C
ommutator surface temperature

  
Commutator bearing noise

  
Pinion bearing noise

Loss (with regenerative dynamometer only)
During the loss test, the motor is manipulated to determine the following losses.

   Rotational
  
Core (DC motor)

  
Field circuit (DC motor)

No Load
During the no load test, voltage is applied to a DC motor in order to rotate the motor a certain speed. In the case of an AC motor, the frequency of the power applied is adjusted until the desired speed is achieved.

    Voltages
  
Frequency (AC motor)

  
Amperages

  
Motor speed

Maximum Speed
During the maximum speed test, voltage is applied to a DC motor until the motor is rotating at a pre-determined speed.  The testing of a AC motor requires that the frequency of the voltage applied to the motor be increased until the motor is operating at the desired speed.

   Voltages
  
Frequency (AC motor)
  
Amperages
   Motor speed
   
Commutator end vibration magnitude and FFT (Fast Fourier Transform)
  
Pinion end vibration and FFT
   
Axial vibration and FFT

Maximum Voltage
During the maximum voltage test, a pre-determined voltage is applied to the motor.

    Voltages
  
Amperages

  
Frequency (AC motor)
   Motor speed
  
Armature voltage FFT
  
Current to ground

Saturation (DC motor only)
During the saturation test, a pre-determined voltage is applied to the armature and three different currents are supplied to the field.

    Armature Voltage
  
Armature Amperage

  
Field Voltage (3 levels)

  
Field Amperage (3 levels)

  
Motor speed (3 levels)

Locked Rotor (AC motors only)
During the locked rotor test, a locking device is engaged such that the motor is not allowed to rotate.  A pre-determined voltage is applied to the motor.

    Voltages
   
Amperages
   
Frequency