Grundfos MGE 71 - Cabling and Operating Conditions; Operating Conditions Overview; Motor Cooling Guidelines

English (GB)
14
6.7 Signal cables
• Use screened cables with a cross-sectional area of min.
0.5 mm
2
and max. 1.5 mm
2
for external on/off switch, digital
inputs, setpoint and sensor signals.
• Connect the screens of the cables to frame at both ends with
good connection. The screens must be as close as possible to
the terminals. See fig. 13.
Fig. 13 Stripped cable with screen and wire connections
• Screws for frame connections must always be tightened
whether a cable is fitted or not.
• The wires in the motor terminal box must be as short as
possible.
6.8 Bus connection cable
6.8.1 New installations
For the bus connection, use a screened 3-core cable with a
cross-sectional area of min. 0.5 mm
2
and max. 1.5 mm
2
.
• If the motor is connected to a unit with a cable clamp which is
identical to the one on the motor, connect the screen to this
cable clamp.
• If the unit has no cable clamp as shown in fig. 14, leave the
screen unconnected at this end.
Fig. 14 Connection with screened 3-core cable
6.8.2 Replacing an existing motor
• If a screened 2-core cable is used in the existing installation,
connect it as shown in fig. 15.
Fig. 15 Connection with screened 2-core cable
• If a screened 3-core cable is used in the existing installation,
follow the instructions in section 6.8.1 New installations.
7. Operating conditions
7.1 Maximum number of starts and stops
The number of starts and stops via the power supply must not
exceed four times per hour.
When switched on via the power supply, the motor will start after
approx. 5 seconds.
If a higher number of starts and stops is desired, use the input for
external start/stop when starting/stopping the motor.
When started via an external on/off switch, the motor will start
immediately.
7.2 Ambient temperature
7.2.1 Ambient temperature during storage and transportation
Minimum -30 °C
Maximum +60 °C.
7.2.2 Ambient temperature during operation
Minimum -20 °C
Maximum +50 °C.
The motor can operate with the rated power output (P2) at 50 °C,
but continuous operation at higher temperatures will reduce the
expected product life. If the motor is to operate at ambient
temperatures between 50 and 60 °C, an oversized motor must be
selected. Contact Grundfos for further information.
7.3 Installation altitude
Installation altitude is the height above sea level of the installation
site.
• Motors installed up to 1000 metres above sea level can be
loaded 100 %.
• Motors installed more than 1000 metres above sea level must
not be fully loaded due to the low density and consequent low
cooling effect of the air. See fig. 16.
Fig. 16 Derating of motor output (P2) in relation to altitude
above sea level
7.4 Air humidity
Maximum air humidity: 95 %.
If the air humidity is constantly high and above 85 %, the drain
holes in the drive-end flange should be open.
See section 5.6 Drain holes.
7.5 Motor cooling
To ensure cooling of motor and electronics, the following must be
observed:
• Position the motor in such a way that adequate cooling is
ensured. See section 5.4 Ensuring motor cooling.
• The temperature of the cooling air must not exceed 50 °C.
• Keep cooling fins and fan blades clean.
TM02 1325 4402 TM05 3973 1812TM02 8842 0904
A
Y
B
A
Y
B
1
2
3
1
2
3
Motor
A
Y
B
A
Y
B
1
2
1
2
Motor
Caution
The motor must not be installed more than
2000 metres above sea level.
TM05 5243 3512
0
0
20
40
60
80
100
500 1000 1500 2000 2500
Altitude [m]
P2
[%]