TDE MACNO DVS200 - Page 22

22  Chapter 4 - Installation User Manual
Cooling
Asynchronous motors are normally cooled by a fan keyed directly on to the motor shaft. Care must be taken, however,
because fan efficiency drops at low motor speeds and the motor may receive insufficient cooling. Discuss motor operating
conditions with the motor manufacturers technical service to ascertain whether it is necessary to provide additional ventilation
(forced cooling).
Functioning at speeds above nominal speed
If a motor has to operate above its nominal speed, contact the manufacturers technical service to ascertain what mechanical
problems (bearing wear, balancing problems etc.) and what electrical losses may occur as a result.
Motor specifications you must know for inverter control
Motor data plate specifications:
- Nominal motor voltage
- Nominal motor current
- Nominal motor frequency
- Nominal motor speed
- Power factor (Cos ϕ)
- Number of terminal pairs
- Connection type (star/delta)
Motor protection
Use of Klixon protectors in motor windings
The contacts of the Klixon overheating protectors can be used to disable the motor either via auxiliary control circuits or
using the input to signal an alarm condition.
NOTA!
The motors Klixon interface circuit can be considered and managed to all intents and purposes like a
signaling circuit. Connections to the motors Klixon protectors must therefore use a shielded twisted
pair cable laid if possible not parallel with other motor cables or at a distance of at least 20 cm (8 inches)
from them.
Drive current limitation
Current limitation can be used to protect the motor against damaging overloads. To do so, the current limit and overload
control parameters must be set so that current to the motor always remains within the motors acceptable limits.
NOTA!
Bear in mind that current limitation can only protect the motor against overheating caused by overload,
and not against overheating caused by inadequate cooling.
Always fit the windings of motors destined for use at low speeds with the necessary temperature control
plates!
Output chokes
In certain cases output chokes may be needed to protect the winding insulation of standard motors. See section 5.7.2.
Output chokes.