4.6.15 Mains Disconnectors - Frame Size D, E and F
Frame size Power & Voltage Type
D P160-P250 380-480V OT400U12-91
E P315 380-480V ABB OETL-NF600A
E P355-P450 380-480V ABB OETL-NF800A
F P500 380-480V Merlin Gerin NPJF36000S12AAYP
F P560-P710 380-480V Merlin Gerin NRK36000S20AAYP
4.6.16 F Frame circuit breakers
Frame size Power & Voltage Type
F P500 380-480V Merlin Gerin NPJF36120U31AABSCYP
F P560-P710 380-480V Merlin Gerin NRJF36200U31AABSCYP
4.6.17 F Frame Mains Contactors
Frame size Power & Voltage Type
F P500-P560 380-480V Eaton XTCE650N22A
F P 630-P710 380-480V Eaton XTCEC14P22B
4.6.18 Motor Insulation
For motor cable lengths ≤ the maximum cable length listed in the General
Specifications tables the following motor insulation ratings are recom-
mended 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 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
4.6.19 Motor Bearing Currents
It is generally recommended that motors of a rating 110kW or higher operating via Variable Frequency Drives 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 drive, motor, driven machine, and motor to the driven machine is required. Although failure due to bearing currents is low and
very 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.
VLT HVAC Low Harmonic Drive Operating In-
structions
4 How to Install
MG.16.A1.02 - VLT
®
is a registered Danfoss trademark 57
4
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