This chapter describes design principles that must be taken into account when designing the
system using the electric machine.
System design
Cooling and temperature measurement
Do not operate the electric machine without correctly dimensioned and operating cooling system.
Mount the electric machine in correct position, see Chapter
When you connect the cooling system make sure that the cooling medium ows freely in and out from the electric
machine with the cooling medium ow equal or higher than rated.
The cooling medium temperature at the inlet of the electric machine must be lower or equal to the rated temperature.
See more detailed information about coolant connection bore speci cations, required coolant
liquid ow and other speci cations in the product data sheet. Rated values can be found from the
electric machine rating plate.
The electric machine has at least one PT100 temperature sensor in the windings. The amount of
the sensors depend on the options chosen. The temperature signal(s) can be read out from the
measurement connector of the machine.
The maximum allowed winding temperature of the electric machine is shown in the rating plate
and in the data sheet.
The PT100 temperature sensor characteristics are: resistance 100 Ω at 0 ºC temperature, and the
resistance increases 0.385 Ω per each 1 ºC increase of temperature.
Insulation lifetime
Heat cycles, environment, moisture, vibrations and similar variables have an effect on the lifetime expectancy of the
insulation of the electric machine. The value of the insulation lifetime expectancy is a calculated value and it is not tested
in practice.
The insulation of the electric machine has the following lifetime expectancy.
Insulation class
Lifetime expectancy
F (150°C)
20 000 h
H (175°C)
20 000 h
100 000 h if driven with maximum winding temperature of 150°C
EM-PMI240
4. Design principles
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Danfoss | Produced By: Danfoss Power Solutions | September 2020 | 17
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