•
•
•
•
N O T I C E
MOTOR THERMISTOR SENSOR MONITORING
VLT® AutomationDrive units with the VLT® PTC Thermistor Card MCB 112 option are PTB-certified for potentially explosive atmos-
pheres.
9.2.5 Vibration and Shock
The drive has been tested according to the procedure based on the following standards:
EN/IEC 60068-2-6.
EN/IEC 60068-2-34.
EN/IEC 60068-2-35.
EN/IEC 60068-2-36.
These tests subject the unit to 0.7 g forces over the range of 18–1000 Hz random in 3 directions for 2 hours. All Danfoss VLT® drives
comply with requirements that correspond to these conditions when the unit is wall or floor mounted and when the unit is moun-
ted within panels bolted to walls or to floors.
9.2.6 Maintenance
Danfoss drive models up to 90 kW are maintenancefree. High-power drives (rated at 110 kW or higher) have built-in filter mats,
which require periodic cleaning depending on the exposure to dust and contaminants. Maintenance intervals for the cooling fans
(approximately 3 years) and capacitors (approximately 5 years) are recommended in most environments.
9.3 Derating
9.3.1 Derating for Running at Low Speed
When a motor is connected to a drive, it is necessary to ensure that the cooling of the motor is adequate.
The level of heating depends on the load on the motor, the operating speed, and time.
Constant torque applications (CT mode)
A problem may occur at low RPM values in constant torque applications. In a constant torque application, a motor may overheat at
low speeds due to less cooling air from the motor integral fan.
Therefore, if the motor is to be run continuously at an RPM value lower than half of the rated value, the motor must be supplied with
extra air cooling (or a motor designed for this type of operation may be used).
Alternatively, reduce the load level of the motor by selecting a larger motor. However, the design of the drive limits the motor size.
Variable (quadratic) torque applications (VT)
In VT applications such as centrifugal pumps and fans, where the torque is proportional to the square of the speed and the power is
proportional to the cube of the speed, there is no need for extra cooling or derating of the motor.
9.3.2 Derating for Low Air Pressure
The cooling capability of air is decreased at lower air pressure.
Max.I
out
(%)
at T
AMB, MAX
A
Altitude (km)
enclosure
B and C
enclosure
T
at 100% I
out
D
100%
91%
82%
0 K
-5 K
-9 K
1 km
2 km
3 km
0 K
-3.3 K
-6 K
e
3
0
b
a
4
1
8
.1
1
AMB, MAX
(K)
Illustration 56: Derating of Output Current Versus Altitude at T
AMB, MAX
for Enclosure Sizes A, B, and C
Below 1000 m (3280 ft) altitude, no derating is necessary. Above 1000 m (3280 ft), the ambient temperature (T
AMB
) or maximum
output current (I
out
) should be derated in accordance with the diagram in
.
AJ300847815559en-000101 / 130R0337 | 103
Danfoss A/S © 2020.09
Mechanical Installation
Considerations
VLT® AQUA Drive FC 202
Design Guide