Preliminary Checks and Calibration
SuperFlow Technologies Group 2-17
2.5.5 Inertia and Parasitic Loss Calibration
Every chassis dynamometer has a built-in inertia factor and parasitic losses.
• The inertia is the equivalent vehicle weight of the rotating components of the dynamometer
and is used in the calculations to determine the required force needed to accelerate those
components. This force is accounted for in the total power calculations for a vehicle under
test. Inertia factor are referenced in pounds (lbs).
• The dynamometer internal parasitic losses, typically bearing friction and aerodynamic drag,
are measured, stored, and accurately accounted for in the power calculations for the vehicle
under test. Parasitic losses are referenced in foot/pounds (ft/lbs).
Verification of the inertia factor and parasitic loss curve should conducted at a frequency set by
the requirements of the testing being done, or as necessary following service to the dynamometer.
2.5.5.1 Inertia Calibration
This process determines the inertia of the system and will set the value into Memory 4, Dyno
Inertia. The value in this memory is automatically used as the inertia factor in the power
calculations.
This procedure is performed without a vehicle on the dynamometer.
From the dyno handheld press
Configure
(the I button) then
Calibrate
(B). Select the “
Inertia
”
option.
The settings have been defaulted for best use, but may be changed if desired. The warm up
routine should be done if the AC motor has not been used in more than 10 minutes. Once the
OK
button is pressed the process will begin automatically. Observe the inertia value displayed after
each cycle. It should only vary by one or two points. Ten cycles will be performed, but the process
may be terminated early by pressing the DONE option. The EXIT option will abort the process.
2.5.5.2 Parasitic Loss Calibration
This routine will spin the roll up to the maximum speed as set in the dynamometer low-level
configuration, then sequentially step down in 10 mph increments down to 0 mph. At each step the
speed will stabilize and the system will collect data. This process takes about 10 minutes.
After completion of this calibration, the loss values are embedded into flash memory and used in
all power calculations.
From the dyno handheld press
Configure
(the I button) then
Calibrate
(B). Select the “
Inertia
”
option.
The settings are fixed and cannot be changed. The warm up routine should be done if the AC
motor has not been used in more than 10 minutes. Once the
OK
button is pressed the process will
begin automatically. Pressing the EXIT button will abort the process.
2.5.5.3 Coastdown Test
Detailed information for this section is pending.
