ABB ACS880-87LC-4000A/4021A-7, Руководство по оборудованию

Страница: 60 / 144

60 Planning the electrical installation
Selecting the DC resistors
For further information, contact your local ABB representative.
Selecting the control cables

General rules
All control cables must be shielded.
As a general rule, the control signal cable shield should be grounded directly in the wind
turbine converter. The other end of the shield should be left unconnected or grounded
indirectly via a high frequency, high voltage capacitor of a few nanofarads. The screen can
also be grounded directly at both ends if they are in the same earth line with no significant
voltage drop between the end points.
Use a double shielded twisted pair cable (see figure a) for analog signals. This type of
cable is recommended for the pulse encoder signals as well. Employ one individually
shielded pair for each signal. Do not use common return for different analog signals.
A double shielded cable is the best alternative for low voltage digital signals but single
shielded twisted multipair cable (figure b) is also acceptable.
Run analog and digital signals in separate, shielded cables.
Relay-controlled signals, providing their voltage does not exceed 48 V, can be run in the
same cables as digital input signals. It is recommended to run the relay-controlled signals
as twisted pairs.
Never mix 24 V DC and 115 / 230 V AC signals in the same cable.

Relay cable
The cable type with braided metallic screen (for example, ÖLFLEX from Lapp Kabel,
Germany) has been tested and approved by ABB.
a
Double-shielded twisted pair cable
b
Single-shielded twisted multipair cable