Motor Insulation; Motor Bearing Currents - Danfoss ADAP-KOOL AKD 102 Operating Instructions Manual

4 Electrical Installation
4.1.13 Mains Disconnectors - Frame Size D
Frame size
D1/D3
D2/D4

4.1.14 Motor Insulation

For motor cable lengths ≤ the maximum cable length listed in the General
4
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.

4.1.15 Motor Bearing Currents

All motors installed with 110 kW or higher power drives should have NDE (Non-Drive End) insulated bearings installed to eliminate circulating bearing
currents. 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.
Standard Mitigation Strategies:
1. Use an insulated bearing
2. Apply rigorous installation procedures
- Strictly follow the EMC Installation guideline
- 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
- Provide a low impedance path from frequency converter to building ground/earth and from the motor to building ground/earth. This
can be difficult for pumps
- Make a direct earth connection between the motor and load machine
- Reinforce the PE so the high frequency impedance is lower in the PE
- Ensure the motor and load motor are aligned
3. Lower the IGBT switching frequency
4. Modify the inverter waveform, 60° AVM vs. SFAVM
5. Install a shaft grounding system or use an isolating coupling between motor and load
6. Apply conductive lubrication
7. If the application allows, avoid running at low motor speeds by using the minimum speed settings of the drive .
8. Try to ensure the line voltage is balanced to ground. This can be difficult for IT, TT, TN-CS or Grounded leg systems
9. Use a dU/dt or sine wave filter
42
Power & Voltage
P110-P132 380-480V & P110-P160 525-690V
P160-P250 380-480V & P200-P400 525-690V
MG.11.O1.02 - ADAP-KOOL
ADAP-KOOL
Type
ABB OETL-NF200A
ABB OETL-NF400A
Nominal Mains Voltage Motor Insulation
≤ 420 V
U Standard U
N
≤ 500 V
420 V < U Reinforced U
N
≤ 600 V
500 V < U Reinforced U
N
≤ 690 V
600 V < U Reinforced U
N
® is a registered Danfoss trademark
®
Drive AKD 102 High Power
= 1300 V
LL
= 1600 V
LL
= 1800 V
LL
= 2000 V
LL