Replacement Of ACBs to implement ARC Flash Settings

Arts Centre Melbourne (ACM) is required to implement settings in the ACB’s of MSB LB01, MSB LB02, MSB LB03 that align with recommendations from recent ARC Flash assessment. Implementing settings on current ACBs causes tripping, new ACB’s with neutral CT’s to be installed, on both incoming and generator supply to match all current setups.

Scope:

1. Replacement of Main ACBs in the following Switchboards:

• MSB-LB-01 – NGV Substation Supply
• MSB-LB-02 – Sturt Kavanagh Substation Supply
• MSB-LB-03 – Central Plant Supply

Existing ACBs:

• Merlin Gerin Masterpact M32 H1, 3200A with ETC trip units

Requirements:

• Supply of new ACBs that can implement the proposed arc flash settings
• Removal and disposal of existing units
• Installation and commissioning
• Integration with existing protection relay systems
• Compliance with arc flash reduction recommendations

2. Replacement of Interlocked Generator Supply ACBs

• Must match the main ACBs in type and rating
• Maintain mechanical and electrical interlock functionality
• Include all necessary accessories and control wiring

3. Implementation of Protection Settings

• Apply the proposed protection settings as detailed in the HV Protection and Arc Flash Report Rev 5.0:

MSB-LB-02 and MSB-LB-03:

• Long Time: 0.85 × In = 2720A
• Short Time: 3 × Ir = 8160A, 0.2s, I²t = Off
• Earth Fault: 0.2 × In = 640A, 0.2s, I²t = Off

MSB-LB-01:

• Long Time: 0.85 × In = 2720A
• Short Time: 3 × Ir = 8160A, 0.2s, I²t = Off
• Earth Fault: 0.2 × In = 640A, 0.2s, I²t = Off

• Ensure neutral CTs are fitted where required to avoid nuisance tripping

• Confirm compatibility with upstream and downstream grading requirements