Field balancing (PT 502)

measurement of imbalance vibrations



  • In rotating machines such as turbines or pumps, vibrations due to imbalance lead to comfort problems or even damage related to overloading.
  • The imbalance of a rotating machine part may cause harmful vibrations in the entire machine. A familiar example is unbalanced tyres on a car.
  • These cause annoying and unpleasant vibrations in the steering.
  • This is why almost all rotating parts are balanced.
  • If this balancing is done not on a particular machine but directly on the machine in operation located on-site, it is known as field balancing.
  • Field balancing is done in four steps. In the first step, the vibrations are used to measure the initial imbalance.
  • In the second step, additional known test imbalances are applied and the system is measured again.
  • In the third step, the balancing is calculated from these two measurements and is applied.
  • The fourth step is a control run to check whether the balancing has been successful.
  • The core of the PT 502unit comprises two flywheels that are driven by an electric motor.
  • Defined imbalances can be attached to the flywheels.
  • At the foot of the motor are two acceleration sensors that measure the imbalance vibrations.
  • The speed is measured by an optical sensor.
  • The motor is mounted on the base plate with vibration-damping rubber elements.
  • The unit is driven at variable speed by a frequency converter.
  • The measured values are transmitted directly to a PC via USB, where they can be analysed using the vibration analysis software that comes included.
  • This analysis software has the following features: dual-channel oscilloscope for investigations in the time range, dual-channel spectrum analyser for investigations in the frequency range, vibration amplifier and balancing module for single and two-plane balancing.

Technical Details:


  • field balancing in one or two planes
  • 2 flywheels with mounting holes for imbalance or balance masses and angular division
  • imbalance or balance masses in different sizes
  • drive motor with variable speed via a frequency converter
  • elastic bearing of the drive motor
  • vibration isolation of the base plate using rubber feet
  • control unit with integrated measuring amplifier
  • instrumentation: optical speed sensor, 2 acceleration sensors for vibration measurement
  • software functions: dual-channel oscilloscope, dual-channel FFT analyser, ramp-up curve, order analysis and balancing
  • GUNT software for data acquisition via USB under Windows 8.1, 10

Technical Data:

  • Flywheels:
    • 2x mass: 1,675kg
    • radius for balance masses: 60mm
    • angular division: 15°
  • Drive motor:
    • speed: 300…3000min-1
    • power: 370W
  • Imbalance or balance masses:
    • 2…10g
    • total imbalance: 2x 42cmg
  • Acceleration sensors
    • frequency range: 1…10000Hz
    • sensitivity: 100mV/g
    • resonant frequency: 32kHz
  • Optical speed sensor
    • scan range: 3…150mm
    • laser class II: 675nm
  • 230V, 50Hz, 1 phase
  • 230V, 60Hz, 1 phase; 120V, 60Hz, 1 phase
  • UL/CSA optional

Dimensions & Weight:

  • L x W x H: 510x450x380mm (experimental unit)
  • L x W x H: 370x360x160mm (control unit)
  • Weight: approx. 39kg (total)

Required for Operation:

  • PC with Windows

Learning Objectives/Experiments:

  • measure and assess machine vibrations
  • occurrence of imbalance vibrations
  • static, dynamic or general imbalance
  • dependence of imbalance vibration on position and magnitude of the imbalance
  • basic principles of balancing
  • field balancing in one plane
  • field balancing in two planes
  • assessment of balancing quality
  • using a computerised vibration analyser

Scope of Delivery:

  • 1 experimental unit
  • 1 control unit
  • 1 set of accessories
  • 1 GUNTsoftware + USB cable
  • 1 set of instructional material


  • single and two-plane balancing


Due to the continuous development of our products, the goods supplied may vary in detail to that illustrated on this Website.