Project planning of the line supply
To determine the maximum possible cable length, the maximum permitted overall impedance of the transformer and supply lines up to the input terminals of the line choke must be taken into account.
For transformers, the following generalized impedance values can be used at 3 × AC 400 V:
- 400 kVA: 16 mΩ
- 630 kVA: 10 mΩ
- 1250 KVA: 8 mΩ
- 2000 KVA: 5 mΩ
The maximum permitted total impedance depends on the line voltage of the supply system. When taking into account the maximum permitted overall impedance, the associated voltage drop and system distortions are so low that the regenerative power supply and other electronic components in the control cabinet can operate reliably.
The maximum permitted overall impedance specified relates to a single regenerative power supply. If several regenerative power supplies are operated on one transformer, only the permissible total resistance value of the regenerative power supply that is furthest away needs to be considered.
You will find the permissible total impedance values in the following table:
Vline in V | Zline in mΩ |
|---|---|
380 | 36 |
400 | 40 |
480 | 57 |
500 | 63 |
Key:
- Ztotal: Overall impedance
- Zline: Permitted overall impedance
- Ztransformer: Transformer impedance
- Zsupply: Supply cable impedance
- Rsupply: Supply cable resistance
- Xsupply: Supply cable reactance
The overall impedance Ztotal consists of the following:
The supply cable impedance Zsupply is composed as follows:
[1] | Utility grid |
[2] | Transformer |
[3] | Line 1 |
[4] | Line 2 |
[5] | Input terminals of the line choke |
[6] | MCR91A-1600.. regenerative power supply |
The total impedance of the system must not be greater than the permitted total impedance.
