The ends of the 3 phases are connected in the star point. The terminal voltage is √3 times the phase
voltage, the mains current is equal to the phase current. The star circuit is marked with the Y symbol.
5.5.3 Selecting on-site fuse protection
The magnetic coupling does not offer an overload protection.
The magnetic coupling's torque is so strong that it does not provide any overload protection
for the motor.
Procedure
1. For the protection of the motor in case of malfunction, always provide fuse protection according to
the regulations applicable for the region.
2. Select a fuse with delayed action characteristic in accordance with the following table.
Motor voltage [V]
Frequency [Hz]
Motor rating [kW]
I
N
[A]
I
max
[A]
230
50
0.25
1.28
4.3
400
50
0.25
0.74
2.5
265
60
0.30
1.28
4.3
460
60
0.30
0.74
2.5
Tbl. 7:
Current values for fuse layout
5.5.4 Connecting the PTC thermistor tripping unit
WARNING
Risk of explosion at increased winding temperature in potentially explosive atmospheres
If the winding temperature of the motor is not monitored, the motor winding could potentially become
a source of ignition. There is a risk of explosion, and consequently the risk of sustaining serious inju-
ries.
► Always establish the connections directed into the motor terminal boxes with a corresponding
PTC thermistor tripping unit of an intrinsically safe electric circuit, suitable for the potentially ex-
plosive area.
– Otherwise, the tripping unit must be installed outside of the potentially explosive area.
Installation
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