Operation At Motors With Electrically Isolated Winding Systems And One Common Winding System - Siemens SINAMICS G130 Engineering Manual

SINAMICS G150
Engineering Information

Operation at motors with electrically isolated winding systems and one common winding system

Operation of G150 parallel converters at motors with two electrically isolated winding systems
The following measures must be taken to balance the motor-side currents:
•
Use of symmetrical power cabling between the two inverters and the motor (cables of identical type with the
same cross-section and length)
Using a motor with two electrically isolated winding systems means that the motor-side inverters can operate with
both, space vector modulation and pulse-edge modulation. Pulse-edge modulation makes it possible to achieve an
output voltage which is almost equal to the value of the input voltage (97 %). (For further details, please refer to the
chapter "Fundamental Principles and System Description", sections "Maximum attainable output voltage with space
vector modulation SVM" and "Maximum attainable output voltage with pulse-edge modulation PEM".)
Despite the current-balancing measures described above, it is not possible to obtain an absolutely symmetrical
current sharing. This means that the currents of the two converter units in a SINAMICS G150 parallel converter are
7.5 % lower than the currents of the individual converters. Allowance is already made for this reduction factor in the
current values in catalog D11 and in the table on the previous pages.
Operation of G150 parallel converters at motors with one common winding system
The following measures must be taken to balance the motor-side currents:
•
Electronic current sharing control in the motor-side inverters (parameter P7035 = 1).
•
Use of symmetrical power cabling between the two inverters and the motor (cables of identical type with the
same cross-section and length)
•
Decoupling measures at the inverter outputs.
Adequate decoupling of the inverter outputs can be achieved either by installing cables of the minimum required
length between the inverter outputs and the motor or, alternatively, by installing motor reactors at the inverter outputs
(option L08).
The table below specifies the minimum required motor cable lengths for SINAMICS G150 parallel converters,
whereby the given length is the distance between the converter output and the motor terminal box along the motor
cable.
Output power SINAMICS G150 cabinet unit
[kW] Version A
380 V to 480 V 3AC
630 6SL3710–2GE41–1AA0
710 6SL3710–2GE41–4AA0
900 6SL3710–2GE41–6AA0
500 V to 600 V 3AC
630 6SL3710–2GF38–6AA0
710 6SL3710–2GF41–1AA0
1000 6SL3710–2GF41–4AA0
660 V to 690 V 3AC
630 6SL3710–2GH41–1AA0
1350 6SL3710–2GH41–4AA0
1500 6SL3710–2GH41–5AA0
Minimum required motor cable lengths for SINAMICS G150 parallel converters
Connecting a motor with one common winding system means that the motor-side inverters can operate only with
space vector modulation, but not with pulse-edge modulation. As a result, the maximum attainable output voltage
equals only approximately 92 % of the input voltage. (For further details, please refer to chapter "Fundamental
Principles and System Description", sections "Maximum attainable output voltage with space vector modulation SVM"
and "Maximum attainable output voltage with pulse-edge modulation PEM".)
Despite the current-balancing measures described above, it is not possible to obtain an absolutely symmetrical
current sharing. This means that the currents of the two converter units in a SINAMICS G150 parallel converter are
7.5 % lower than the currents of the individual converters. Allowance is already made for this reduction factor in the
current values in catalog D11 and in the table on the previous pages.
SINAMICS Engineering Manual – May 2008
208/396
© Siemens AG
Minimum motor cable
length
[m]
13
10
9
18
15
13
20
18
15