KT-420-4 // PDF Download
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Safety signs attached to the compressor
WARNING
Strong magnetic field!
Keep magnetic and magnetizable objects away from compressor!
Persons with cardiac pacemakers, implanted heart defibrillators or metallic implants: maintain a clearance
of at least 30 cm!
Special voltage motors
If the motor is running at maximum operating current already at standard conditions, a special voltage motor may
be useful in order to achieve a larger regulating range. It ensures that even above supply frequency, a constant
voltage-frequency ratio U/f can be maintained. A constant torque is available over the entire application range.
!
!
NOTICE
Compressor and motor damage in case of exceeding speed!
Observe the upper speed limit of the compressor! See application range.
Depending on design and/or allowed speed range of the compressor, the preferrable motor option is (with regard to
power supply 400 V/3/50 Hz):
• 40S: 230 V/3/50 Hz (+73% compressor current) at full motor torque – observe maximum allowed speed of the
compressor! (following figure, graph ③)
①
②
③
0
400
300
200
100
0
10
90
20
30
40
50
60
70
80
87
U
[V]
230
f
[Hz]
333
Fig. 13: Voltage increase depending on the frequency for different motors
①: 400 V/3/50 Hz
②: 400 V/3/60 Hz
③: 230 V/3/50 Hz
With this design, the operating current at graph ② is 1.2 times higher than in the case of 400 V/50 Hz; at graph ③ it
is 1.73 times higher. This increases frequency inverter costs resp. the frequency inverter has to be chosen accord-
ingly.
Information
A standard motor allows the direct operation of the compressor on the power grid with contactors in case of
a failure of the frequency inverter (emergency mode).
