Inverter control cabinet control cable selection and wiring principle

1. For Class I signal cable, shielded cable must be used. The millivolt signal and strain signal in Class I signal should be shielded twisted pair cable. It should also ensure that the shield layer is only grounded at one point and should be grounded well. In this way, electromagnetic interference and static interference can be greatly reduced.

2. For Class II signals, shielded cables should also be used. For Class II signals used for control and interlocking of the molded-in and outgoing signals, shielded cables must be used. Shielded twisted-pair cables are preferred. It is forbidden to use part of the core wire of a multi-core cable for transmitting Class I or Class II signals, and some core wires for transmitting Class III or Class IV signals.

3. It is strictly forbidden to bundle the I and II signals together with the Class IV signal. It should be handled as a 220V power cable. The Class IV signal cable should be routed together with the power cable. A shielded twisted pair cable should be used. It is absolutely forbidden to bundle the high-power switch output signal line, power line, power line and other cables with the I and II type signal cables of the variable frequency speed control system.

4. For Class III signals, it is allowed to be routed together with the 220V power line (ie, the same as the Class IV signal), or it can be routed together with the I and II signals. However, Class III signals must also be shielded cables, preferably shielded twisted pair cables, and are more than 15 cm away from Class I and II signal cables. It is forbidden to distribute several core wires of the same signal in different cables (such as three-wire thermal resistance).

In field cable laying, it is necessary to effectively separate cables that are prone to interference such as Class III and IV signal cables and power cables, so as to maintain a certain safe distance (such as 15cm or more) with the cables of Class I and II signals laid on site. .

Signal cables and power cables should be routed with different cable troughs. When entering the inverter cabinet, they should be as far apart as possible. When these two cables do not meet the separate wiring requirements, they must all use shielded cables (or shielded twisted pair cables) and should meet the following requirements:

1. If the distance between the signal cable and the power cable is less than 15 cm, a metal partition for shielding must be placed between the signal cable and the power cable, and the partition should be grounded.

2. When the signal cable and the power cable are installed separately in the vertical or horizontal direction, the distance between the signal cable and the power cable should be greater than 15 cm. For some applications with particularly high interference, such as when the power cable is connected with an AC 220V voltage and an inductive load with a current above 10A, and the power cable does not have a shielding layer, it is required to be separated from the vertical direction of the signal cable. Above 60cm.

3. When the two sets of cables are perpendicular to each other, if the power cable does not have a shield, the iron plate with a thickness of 1. 6 mm or more is used to cover the intersection.

In order to reduce the interference of the analog quantity from the inverter and other equipment, the signal line of the control inverter should be separated from the high-voltage circuit (main circuit and sequence control circuit). The distance should be more than 30cm. Even in the control cabinet, it is necessary to maintain such wiring specifications. The signal cable must not exceed 50m in length. The metal tube or metal hose for protecting the signal line should be extended to the control terminal of the inverter to ensure complete separation of the signal line from the power line. The analog control signal line should use a twisted pair shielded wire with a wire size of 0.5~2mm2. When wiring, the cable stripping should be as short as possible (5~7mm). At the same time, the shielding layer after stripping should be wrapped with insulating tape to prevent the shielded wire from coming into contact with other equipment and introducing interference.