4.6.16 F Frame circuit breakers
Frame size Power & Voltage Type
F P450 380-480 V Merlin Gerin NPJF36120U31AABSCYP
F P500-P630 380-480 V Merlin Gerin NRJF36200U31AABSCYP
Table 4.45
4.6.17 F Frame Mains Contactors
Frame size Power & Voltage Type
F P450-P500 380-480 V Eaton XTCE650N22A
F P560-P630 380-480 V Eaton XTCEC14P22B
Table 4.46
4.6.18
Motor Insulation
For motor cable lengths ≤ the maximum cable length
listed in 8 General Specifications the following motor
insulation ratings are recommended because the peak
voltage can be up to twice the DC link voltage, 2.8 times
the mains voltage, due to transmission line effects in the
motor cable. If a motor has lower insulation rating it is
recommended to use a dU/dt or sine wave filter.
Nominal Mains Voltage Motor Insulation
U
N
≤ 420 V
Standard U
LL
= 1300 V
420 V < U
N
≤ 500 V Reinforced U
LL
= 1600 V
Table 4.47
4.6.19
Motor Bearing Currents
It is recommended that motors of a rating 110 kW or
higher operating via frequency converters should have
NDE (Non-Drive End) insulated bearings installed to
eliminate circulating bearing currents due to the physical
size of the motor. To minimize DE (Drive End) bearing and
shaft currents proper grounding of the frequency
converter, motor, driven machine, and motor to the driven
machine is required. Although failure due to bearing
currents is low and dependent on many different items, for
security of operation the following are mitigation strategies
which can be implemented.
Standard Mitigation Strategies:
1. Use an insulated bearing
2. Apply rigorous installation procedures
Ensure the motor and load motor are aligned
Strictly follow the EMC Installation guideline
Reinforce the PE so the high frequency
impedance is lower in the PE than the input
power leads
Provide a good high frequency connection
between the motor and the frequency converter
for instance by screened cable which has a 360°
connection in the motor and the frequency
converter
Make sure that the impedance from frequency
converter to building ground is lower that the
grounding impedance of the machine. This can
be difficult for pumps- Make a direct earth
connection between the motor and load motor.
3. Apply conductive lubrication
4. Try to ensure that the line voltage is balanced to
ground. This can be difficult for IT, TT, TN-CS or
Grounded leg systems
5. Use an insulated bearing as recommended by the
motor manufacturer (note: Motors from reputable
manufacturers will typically have these fitted as
standard in motors of this size)
If found to be necessary and after consultation with
Danfoss:
6. Lower the IGBT switching frequency
7.
Modify the inverter waveform, 60° AVM vs.
SFAVM
8. Install a shaft grounding system or use an
isolating coupling between motor and load
9. Use minimum speed settings if possible
10. Use a dU/dt or sinus filter
4.6.20
Control Cable Routing
Tie down all control wires to the designated control cable
routing as shown in the picture. Remember to connect the
shields in a proper way to ensure optimum electrical
immunity.
How to Install VLT Automation Low Harmonic Drive Operating Instructions
50 MG34O202 - VLT
®
is a registered Danfoss trademark
44
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