L1
L1
L2
L2
L3
L3
N
N
ACM3.1
V
BB-L1
V
BB-L2
V
BB-L3
V
L1
V
L2
V
L3
L2
L1
L3
Controlled
equipment
Breaker
Phase
sequence
meter
1
2
4.2.2 Checking the voltage across the breaker when synchronised
If it is possible to keep the genset and busbar synchronised, check the voltage across the breaker. Do this test before closing
the breaker for the first time.
DANGER!
There must not be voltage across the breaker when the generator and busbar are synchronised. A voltage
difference is extremely dangerous and can result in personal injury or death, and serious equipment
damage.
To check the voltage across the breaker:
1. Requirements:
• The breaker must be disconnected.
• There must be voltage on the busbar.
• The genset must be running.
2. Use manual control, or external equipment (for example, a PLC) to keep the generator and busbar synchronised.
3. Check that the generator and busbar are synchronised (for example, using a synchroscope).
4. When the generator and busbar are synchronised, use a multimeter to measure the voltage across the breaker for L1
(connections shown in red below). Then, measure the voltage across the breaker for L2, then for L3 (connections shown
in blue).
GPU 300 Commissioning guidelines 4189341033 UK
www.deif.com
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