Diesel Gen-set Operation Instructions
67
with safe operation procedures of malfunctioned Gen-set.
At first, carry out all mechanical and electrical safe operations related to the Gen-set
and site, in order to ensure operation safety of alternator.
Complete short connection of output end of Gen-set with short-circuit plates which
can withstand rated current of alternator.
Disconnect connecting wires (F1 and F2 connecting wire of AS440 and AS480, F+
and F- connecting wire of SE350) of excitation stator (magnetic field) on AVR.
Add a direct-current electrical source between the disconnected two conductors
(connect F1 or F+ to positive electrode and connect F2 or F- to negative electrode)
and this direct-current electrical source must be adjustable in a range of 0~24V and is
able to provide 2.0A current to an extreme.
Connect a proper AC ammeter to measure short-circuit current.
Adjust voltage of direct-current power source to zero at first and then start the
Gen-set. Increase direct-current voltage slowly so as that current flows in coil of
excitation stator (magnetic field). When excitation current increases, the stator current
in short-circuit state will increase also. Be sure to measure current of stator so as that
it is not 80% higher than rated current.
Please perform following measurements every 30 minutes:
Stop the Gen-set, disconnect externally connected exciting DC power source, and
then measure, record and tabulate insulation resistance of stator coil. The measured
figure shall be compared with typical curve and the drying process will be completed
when insulation resistance reaches to the value specified in “typical drying curve”.
Once the insulation resistance reaches to 1M
Ω
, remove the DC power source and
reconnect magnetic field lead of exciter (F1 and F2 connecting wire of AS440 and
AS480, F+ and F- connecting wire of SE350) to terminal of AVR. Restore the
Gen-set and reinstall all cover plates to carry out commissioning of the Gen-set again.
