Substation and MCC lab · Level 6 of 8
Fault level and breaker check
Level 6 of 8 in the Substation and MCC lab: a free substation and MCC exercise at Advanced level. A bigger transformer goes in. Work out the new fault level and find out which breakers on the board can no longer break it.
Free · no download. Your work is saved on this device. Updated 18 Oct 2026.
The brief
- Client
- Penhallow Textiles
- Site
- Substation upgrade, LV board A
- Work order
- WO-MCC-106
- Task code
- MCC-06
- Difficulty
- Advanced
- Type of work
- Protection
A bigger transformer goes in. Work out the new fault level and find out which breakers on the board can no longer break it.
Skills you practise
- Prospective fault current
- Transformer impedance
- Breaking capacity
- Breaker replacement
What the test checks
The acceptance test marks the skills this level practises.
- Prospective fault current
- Transformer impedance
- Breaking capacity
- Breaker replacement
In this lab
- Safe isolation: lock, tag, prove, test, earth
- Cables, breakers, relays and fault levels
- A 3D switchroom and transformer bay
Levels in the Substation and MCC lab
Previous: Grade the incomer relayNext: Correct the power factor
Part of the Substation and MCC lab
Walk a small substation, isolate a motor bucket safely, grade a relay and fault-find a motor control centre.
About the Substation and MCC lab
Feeds these internships: Control Panel Design and Wiring, Commissioning and Maintenance, Electrical Design.