ABB Industrial Drive ACS880-7207LC and -7307LC DC input unit

Operating principle

The DC in-line unit provides a connection between two DC systems. The two most common applications are:

• Connection of the external DC system to the transmission DC bus (e.g. generator connection)

• Liaison bus connection, that is, the transmission DC bus system is divided into two or more parts.

For both applications, ACS880-7207LC or ACS880-7307LC DC feed line units are available:

• ACS880-7207LC can isolate (disconnect) two DC systems, and switch on and off load current, can also be in

Cut off the fault current to a certain extent.

• The ACS880-7307LC can isolate (disconnect) only two DC systems, and cannot turn on or off the load current, nor

Cut off the fault current.

The main component required for both the ACS880-7207LC and ACS880-7307LC units is the DC isolation switch/circuit breaker.

The size and connection of the DC isolation switch varies with its use.

Dc cable selection and wiring

This section applies only to DC input units equipped with external power terminals (Option +G316).

■ Suggested cables

Customers (or system integrators) purchase and connect their own DC cables. Three - or four-core shielded cables can be used:

• If a four-core shielded cable is used, two cores are used as positive wires, the other two cores are used as negative wires, and the shielding layer is used for protective grounding.

• If a three-core shielded cable is used, use one core as a positive wire, the other as a negative wire, and use the remaining core and shielding layer for protective grounding.

■ Typical cable size/type

■ Reduce electromagnetic interference

The customer (or system integrator) must comply with these rules to minimize electromagnetic interference caused by rapid current changes:

• The entire wiring needs to be shielded at all points, either by using shielded cables or metal housings. Unshielded single-core cables can only be used for cabling in the cabinet and can effectively inhibit radiation interference.

• Install cables away from other cable cabling.

• Avoid long distance parallel wiring with other cables. The minimum parallel wiring spacing should be 0.3 m.

• Cross other cables at the correct Angle.

To reduce radiation interference, the cable should be as short as possible.

■ EMC compliance for overall installation

ABB does not verify that external power cables meet EMC requirements. The customer (or system integrator) must consider EMC compliance for the overall installation.

Electrical safety precautions

1. Clearly identify the workplace and equipment.

2. Disconnect all possible voltage sources. Make sure you cannot reconnect. Lock and tag.

• Disconnect the main isolation device of the drive.

• If there is a charge switch, disconnect it.

• Turn off the isolation switch of the power transformer. (The main isolation device in the transmission cabinet will not disconnect the voltage of the main bus in the transmission cabinet AC input circuit.)

• If the drive is equipped with a DC/DC (DC/DC) converter unit (optional) or DC (DC) feeder unit (optional) : Turn on the DC disconnecting switch of the unit ([Q11], optional +F286 or +F290). Open the isolation device of the accumulator connected to the device (located outside the drive cabinet).

• Disconnect the auxiliary voltage isolation switch (if any) to disconnect the dangerous voltage source connected to the drive.

• In the water cooling unit (if any), turn on the isolation switch of the cooling pump.

• If a permanent magnet motor is connected to the drive, disconnect the motor from the drive using a safety switch or other means.

• Disconnect the control circuit from the external dangerous voltage.

• After disconnecting the transmission power, be sure to wait five minutes for the intermediate circuit capacitor to discharge before proceeding.

3. Avoid contact with any other live parts in the workplace.

4. Take special precautions when working near exposed wires.

5. Measure to determine that the device is powered off. Use a qualified voltage tester. If measurements require the removal or removal of cover plates or other cabinet structures, comply with local laws and regulations regarding live work (including, but not limited to, shock and arc protection).

• Verify that the voltage measuring instrument meets the voltage measuring range before and after measuring the equipment.

• Ensure that the voltage between the transmission input power terminal (L1, L2, L3) and the ground (PE) bus is zero.

• Ensure that the voltage between the transmission output terminals (T1/U, T2/V, T3/W) and the ground (PE) bus is zero.

It's important! When repeated measurements are made, the tester should also be set to DC voltage. Measurement between phases and ground. Due to the leakage capacitance of the motor circuit, there is a risk of dangerous DC voltage charging. This voltage remains charged even long after the transmission power is turned off. The measurement operation releases voltage.

• Ensure that the voltage between the transmission DC terminals (UDC+ and UDC-) and the ground (PE) terminals is zero. In a cabinet drive, measure between the drive DC busbar (+ and -) and the ground (PE) busbar.

6. Install temporary grounding according to local regulations.