Dynamometer Defined, Features, and Benfits

Dynamometer Defined

dy·na·mom·e·ter [dahy-nuh-mom-i-ter]
A dynamometer or "dyno", is a test instrument used to measure torque and speed, which is used to calculate power of a device such as an engine, electric motor, pump, transmission, or generator/alternator. Dynamometers can be either motoring, in which a dynamometer has a motor that can drive the device under test, and/or absorbing where the torque and speed is determined by the power produced.

Dynamometer Features

FeaturesEddy CurrentACDCWater Brake
Motoring AbilityNoYesYesNo
InertiaVariesLowHighLow
Control StabilityGoodExcellentVery GoodLow
Speed CapabilityHighHighModerateHigh
Power Line RegenerationNoYesYesNo
Control ResponseModerateFastestFastSlow
Cooling RequirementsHighLowLowHigh
Electrical RequirementsLowHighHighNone
TechnologyOldNewOldOld
Power RangeHighModerateModerateHigh

Dynamometer Advantages and Disadvantages

Dynamometer Type Advantages Disadvantages
Eddy Current
  • Precise Control
  • Low Maintenance
  • Widely accepted in the automotive industry
  • High Inertia
  • Moderate Cost
AC
  • Motors and Absorbs
  • Very Low Inertia
  • Very Fast Response
  • Line Regenerative
  • High Cost
  • Requires high amperage electrical service
DC
  • Motors and Absorbs
  • Fast Response
  • Blower Cooled (No coolant required)
  • Line Regenerative
  • High Cost (Dynamometer and Power Amplifier)
  • High Inertia
  • Requires high amperage electrical service
Water Brake
  • Low Cost
  • Low Inertia
  • Difficult to Control
  • High Maintenance