02 IMPORTANT SAFETY INFORMATION
3BHS213401 E01 REV H ACS1000 AIR-COOLED USER MANUAL 23/184
2.8 Important note - main circuit breaker
The main circuit breaker (MCB) is a major protection device of the drive. If a serious fault occurs
in the drive, the MCB must disconnect the main power supply to the drive immediately. The
main power supply must be disconnected without delay on an open or trip command from the
drive to prevent hazard to the personnel and further damage to the equipment. The MCB is
located on the primary side of the converter transformer.
Figure 2-2: Drive system overview
The MCB is a switching device that disconnects the power supply whenever required by the
process or when a fault occurs. Typical MCBs are:
- Vacuum circuit breakers
- SF6 circuit breakers
- Fused contactors or motor control centers
A dedicated protection relay is used for:
- Transformer or converter primary cable protection (DTL)
- Transformer protection (if applicable)
- Transformer secondary cable protection (if applicable)
- Backing up the drive protection
In general, these protective measures are not included in the drive as provided by ABB.
(1) Main power supply
(2) MCB control interface
(3) Higher-level control system
(4) Local MCB control
(5) MCB
(6) Protection relay
(7) Converter transformer
(8) Drive
(9) Motor
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4
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