Electrical parreling generators and load sharing

Question 1

requirements for connecting an incoming alternator to A live bus bar

Answer 1

1. same voltage
2. same frequency
3. same phase angle
4. same phase sequence

Question 2

conquences of incorrect paralleling

Answer 2

1. damage to the prime mover
2. over heating or fire on eletrical components
3. prime mover failure, blackout

Question 3

how is voltage monitored

Answer 3

voltmeter, it is adjusted by increasing or decreasing the excitation on the kvar controls

Question 4

how is frequency monitored

Answer 4

frequency meter and is adjusted by increasing or decreasing the kW on the govenour controls

Question 5

phase angle and sequence

Answer 5

synchroscope, the clock should be travelling steadily clockwise amd once in the 5 to 12 position close the breaker

Question 6

how to manually couple a 2nd auxiliary gene to the mswbd and balance the load

Answer 6

1. ensure safe and ready to start, do the pre start checks.
2. select mannual mode
3. run up the incoming gene
4. turn on the synchroscope
5. monitor the voltage and frequency, adjust if needed using controls
6. once synchroscope is traveling steadily and in the 5 to 12 position close the breaker.
7. Once closed manually load share using the kW and kvar controls, increasing and decreasing simultaneously.
8. turn off the synchroscope and put gene back into auto

Question 7

procedure for taking an ac gene off load

Answer 7

automatically - select stop, put in pms, load will automatically decrease.

manually - slowly reduce the kW load using the govenour control, once its below 100 kW the breaker can be opened. Run the generator for a few minutes in Idle then stop

Question 8

isolation a gene in order that work may safely be carried out

Answer 8

Obtain a permit to work, stop the generator confirm it stopped, rock out the circuit breaker fully. engage Earth and lock into position. Put signage across and a permit to work. Remove cover on generator to access bus bar. Prove dead using line tester, once proved dead get a permit to work confirm the text have been carried out so that work can begin.

Question 9

4 electrical protective devices

Answer 9

1. reverse power
2. under voltage protection
3. main circuit breaker
4. preference trip

Question 10

reverse power trip?

Answer 10

Reverse power trip is where is a generator starts 2 mortor and starts to take power from the Bus Bar it can cause failure of the prime mover you can tell a reverse power trip has happened and by kW going negative.

Question 11

under voltage protection

Answer 11

A prevent a Dead generator from being connected. It also trips the breaker when a severe voltage drop occurs usually around 50%. When the voltage drops the mechanical latch lifts which opens the breaker contacts.

Question 12

preference trips

Answer 12

All non-essential services in the event of an over current will be tripped to protect the generators, this will will be done in stages.

Question 13

main circuit breaker over current

Answer 13

prevents damage by overcurrent, usually by overheating