Lenze DSD - Manual (Page 440)

17 Restrictions of the drive dimensioning
17.26 Cooling servo motors without gearbox via mounting flange
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Lenze · Drive Solution Designer · Manual · DMS 4.2 EN · 12/2013 · TD23
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17.26 Cooling servo motors without gearbox via mounting flange
If naturally ventilated motors of the MCS series are used, a most of the heat must be dissipated via
the mounting flange. If this process is neglected, the motor becomes impermissibly hot if operated
with rated data. If a geared motor is used, the heat is reliably dissipated via the housing of the gear-
box.
A motor without gearbox must be mounted to a thermally conductive/isolating plate or chassis.
The operation with rated data is permissible if a mounting plate is used which complies with at least
the following requirements:
• The plate is made of steel and the heat of the steel plate is dissipated through free convection.
• The dimensions of the steel plate are
• 270 × 270 mm for MCS06,
• 330 × 330 mm for MCS09,
• 450 × 450 mm for MCS12/14/19.
17.27 Permanent load at low motor speeds for applications acc. to UL
For machines and plants with UL approval, a special thermal protection for motors may be required.
Advanced thermal protection acc. to UL 2111 (standard for overheating protection for motors) is
achieved by two measures:
A. Activated I
2
t monitoring in the inverter.
B. Thermal encoder with UL approval. In addition, the temperature evaluation in the inverter must
comply with the requirements acc. to UL.
If the I
2
t monitoring in the inverter is used, the permanent torque of the motor must be reduced at
low speeds (derating).
• Naturally ventilated and forced ventilated motors:
• Reduce the torque to 99 % of the rated torque in a frequency range of 0 … 20 Hz.
• Self-ventilated motors:
• For low frequencies, the torque must comply with the values provided by the characteristic
curve (M-n characteristic) of the motor.