Single-speed motors
Single-speed motors are suitable for direct and star-delta starting. If the wiring to the unit outside
was done by TRANE, standard wiring is for direct start. Wiring for star-delta start is possible on
request.
All single-speed motors are suitable for frequency converters. The frequency range of the motor is
shown in Figure 111.
Figure 111: Workspace of single-speed motors
Speed range in which the motor reaches the rated output:
Nn x 0,6 bis Nn x 1,75
Nmin = 0,1 x Nn
Minimum performance by Nmin: 0,1 x Pn
Pn....................Nom. capacity
Nn....................Nom. RPM
Nmin................Min. RPM
Two or three speed motors
These motors are always designed for direct start in each stage.
These motors are not suitable for frequency converter! A frequency converter
destroys the motor winding!
For CCEB units the following on site equipment is required:
1) Motor without frequency converter: motor protection switch
A motor protection switch must always be used when the motor is not running with a frequency
converter.
The motor protection switch must be equipped with a thermal switch to protect the motor winding
and with an electro-magnetic switch (short-circuit protection). The function of the motor protection
switch is to protect the motor against destruction by switching all pools in case of:
- Not start
- Overload
- Decrease of mains voltage
- Failure of a conductor in the three phase power supply
2) Motor with frequency converter: circuit braker is sufficient
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