Maximum Peak Voltage At The Motor Terminals; Reducing Bearing Currents; Table 6-7 Maximum Peak Voltage At The Motor Terminals - Siemens 1LA8 Operating Instructions Manual

Electrical connection
6.5 Connecting the auxiliary circuits
Dangerous voltage via the converter
As long as the feeding converter is switched on, or the DC link of the converter is not
discharged, there can be a voltage at the motor terminals even when the rotor is not moving.
The voltage is up to 1000 V, depending on the converter type.
Ensure that the five safety rules (Page 15) are followed before working on the motor.
6.5.5.2

Maximum peak voltage at the motor terminals

The maximum peak voltage values at the motor terminals are listed in the table as limit values
for the insulation system:
Table 6-7
Rated motor voltage [V]
≤ 500 V
> 500 to 690 V
NOTICE
Insulation damage caused by cable reflections
Cable reflections can double the voltage load at the motor or at the terminals. This can
damage the insulation system and result in complete destruction of the machine.
6.5.5.3

Reducing bearing currents

Taking the following actions will reduce the bearing currents:
● Ensure that the contacts are established over a large area. Solid copper cables are not
Equipotential bonding conductors:
Use equipotential bonding conductors:
● Between motor and driven machine
● Between motor and converter
● Between the terminal box and the RF grounding point at the motor enclosure.
78
WARNING
Maximum peak voltage at the motor terminals
suitable for high frequency grounding because of the skin effect.
Maximum peak voltage at the motor terminals Û
Conductor - conductor
1500 V
Rise time 0.5 μs
2250 V
Rise time 0.4 μs
Conductor - ground
1100 V
Rise time 0.5 μs
1500 V
Rise time 0.4 μs
SIMOTICS TN Series N-compact 1LA8
Operating Instructions 05/2016
max
DC link
750 V
1125 V