Abstract
This paper describes the design of a calorimeter that is
suitable for measuring power losses in electrical motors of up to 300 kW
(402 hp). Refined from the two previous generations, this calorimeter is of
air-cooled open type. Accurate control of the air flow rate and temperature
gradients between the inside and outside walls of the calorimeter ensures
that a repeatable and durable measurement environment is achieved. Dur-
ing the design stage, attention is focused on heat leakage prevention and
reduction in the length of the testing procedures. Heat leakage is mitigated
by appropriate insulation and active temperature control over all walls and
connection ports. In selecting the materials for the structure, lightweight
aluminum and polystyrene are used in sandwich form to reduce the
thermal time constant and, thus, the operational time for the calorimeter
to reach its equilibrium. After the calorimeter is commissioned, further
reduction in the lengthy test procedures is realized by boosting the initial
power loss value of the motor under test. That is, some additional resistive
heaters are installed inside the calorimeter and operate in conjunction
with the test motor. This push–pull technique can guarantee a constant
combined power loss during operation, which is assumed to be the final
value of motor loss. By predefining a suitable motor loss and a tolerance,
it is possible to dynamically control the input power to the dc heaters from
the start and to shut down the heaters once the motor loss value enters
the tolerance selected. Calibration results confirm the effectiveness and
accuracy of the calorimeter.
suitable for measuring power losses in electrical motors of up to 300 kW
(402 hp). Refined from the two previous generations, this calorimeter is of
air-cooled open type. Accurate control of the air flow rate and temperature
gradients between the inside and outside walls of the calorimeter ensures
that a repeatable and durable measurement environment is achieved. Dur-
ing the design stage, attention is focused on heat leakage prevention and
reduction in the length of the testing procedures. Heat leakage is mitigated
by appropriate insulation and active temperature control over all walls and
connection ports. In selecting the materials for the structure, lightweight
aluminum and polystyrene are used in sandwich form to reduce the
thermal time constant and, thus, the operational time for the calorimeter
to reach its equilibrium. After the calorimeter is commissioned, further
reduction in the lengthy test procedures is realized by boosting the initial
power loss value of the motor under test. That is, some additional resistive
heaters are installed inside the calorimeter and operate in conjunction
with the test motor. This push–pull technique can guarantee a constant
combined power loss during operation, which is assumed to be the final
value of motor loss. By predefining a suitable motor loss and a tolerance,
it is possible to dynamically control the input power to the dc heaters from
the start and to shut down the heaters once the motor loss value enters
the tolerance selected. Calibration results confirm the effectiveness and
accuracy of the calorimeter.
Original language | English |
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Pages (from-to) | 2365-2367 |
Journal | IEEE Transactions on Instrumentation and Measurement |
Volume | 58 |
Issue number | 7 |
DOIs | |
Publication status | Published - 1 Jul 2009 |