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4.1
TESTING CONSIDERATIONS
A number of factors must be taken into consideration before running a test including safety, accuracy,
power dissipation, fixturing, couplings, windage, friction, vibration, cogging, eddy currents and
temperature rise. The following sections describe these factors, and their effects, in further detail.
4.1.1
S
afeTy
For general safety considerations, please follow these few common-sense rules:
•
Be sure that your coupling is adequately rated for the speed and torque that you intend to
run.
•
Make sure all rotating elements are covered.
•
Always wear safety glasses when working around dynamometer test equipment.
•
Do not wear loose clothing or ties when working around dynamometer test equipment.
•
Never allow anyone to stand close to the side of, or lean over, a rotating shaft coupling.
•
Insulate electrical (internal and external) motor connections.
C
aution
•
Always connect the motor frame to a high current capacity (water pipe) earth ground.
•
Be sure the motor control circuit breakers cannot be bypassed by accident. Variable auto-
transformers are especially hazardous!
•
When operating dynamometers with blowers, hearing protection must be worn.
4.1.2
a
CCuraCy
Following, is a list of several factors that affect the apparent accuracy of the torque readout.
Full Scale Torque Calibration: This setting will be affected by an internal temperature
•
rise of up to ±0.0015% FS/°C. For more information on full-scale torque setup and
troubleshooting, refer to Section 6.4 – Calibration Procedure and Section 8.1.3 – Full Scale
Torque.
Zero Offset: This setting is affected by an internal temperature rise of up to ±0.002%
•
Reading/°C. For more information on zero offset setup and troubleshooting, refer to Section
6.4 – Calibration Procedure and Section 8.1.2 – Zero Balance.
Coupling Losses: If the coupling becomes hot to the touch, or if the dynamometer or
•
motor vibrate after a period of running, coupling loss error could occur up to several percent
depending on the size of the motor and dynamometer. For more detail, refer to Section 4.1.4
– Fixtures and Couplings.
Windage: Negligible at speeds up to 6000 rpm. This effect is described more extensively
•
in Section 4.1.5 – Windage.
•
Mechanical Friction: Generally negligible on HD-400 series dynamometers and larger.
On HD-106 and HD-100 the user is cautioned to be aware of the effects that friction may
cause. For more detail, refer to Section 4.1.6 – Friction.
4. Testing
:
a
-
power
line fault into the dynamometer frame Could pass a
transient surge through all interConneCted instruments
Computer in use or operating personnel with dangerous and Costly
!
ConsequenCes
35
,
any
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