Motor Insulation; Motor Bearing Currents; Brake Resistor Temperature Switch; Control Cable Routing - Danfoss VLT AutomationDrive FC 302 Operating Instructions Manual

How to Install

3.5.17 Motor Insulation

For motor cable lengths ≤ the maximum cable length
listed in , the recommended motor insulation ratings are in
Table 3.50. The peak voltage can be up to twice the DC
3 3
link voltage, 2.8 times the mains voltage, due to
transmission line effects in the motor cable. If a motor has
a lower insulation rating, use a dU/dt or sine wave filter.
Nominal Mains Voltage
≤ 420 V
U
N
420 V < U ≤ 500 V
N
500 V < U ≤ 600 V
N
600 V < U ≤ 690 V
N
Table 3.50 Motor Insulation at Various Nominal Mains Voltages

3.5.18 Motor Bearing Currents

All motors installed with FC 302 90 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
2a
2b
2c
2d
2e
2f
3. Lower the IGBT switching frequency
4. Modify the inverter waveform, 60° AVM vs.
SFAVM
70
VLT
Motor Insulation
Standard U = 1300 V
LL
Reinforced U = 1600 V
LL
Reinforced U = 1800 V
LL
Reinforced U = 2000 V
LL
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
®
Automation Drive FC 300 Operating Instructions
5. Install a shaft grounding system or use an
isolating coupling
6. Apply conductive lubrication
7. Use minimum speed settings if possible
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 sinus filter

3.5.19 Brake Resistor Temperature Switch

Torque: 0.5-0.6 Nm (5 in-lbs)
Screw size: M3
This input can be used to monitor the temperature of an
externally connected brake resistor. If the input between
104 and 106 is established, the frequency converter trips
on warning/alarm 27, Brake IGBT. If the connection is
closed between 104 and 105, the frequency converter trips
on warning/alarm 27, Brake IGBT.
Install a KLIXON switch that is normally closed. If this
function is not used, short circuit 106 and 104 together.
Normally closed: 104-106 (factory installed jumper)
Normally open: 104-105
Terminal No.
106, 104, 105
Table 3.51 Terminals for Brake Resister Temperature Switch
NOTICE
If the temperature of the brake resistor gets too high
and the thermal switch drops out, the frequency
converter stops braking. The motor starts coasting.

3.5.20 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.
Fieldbus connection
Connections are made to the relevant options on the
control card. For details, see the relevant fieldbus
instruction. The cable must be placed in the provided path
inside the frequency converter and tied down with other
control wires (see illustrations).
MG33U402 - Rev. 2013-12-16
Function
Brake resistor temperature switch.