MMD Equipment 25S-3A3 - Manual (Page 49)

6. Periodic Inspection/Maintenance
6-7
6.5 Maintenance Every 250 Hours
6.5.1 Change Engine Oil
Follow the same procedure for changing engine oil as mentioned in 6.4.1.
6.5.2 Check Insulation Resistance
When the generator has not been operated for a long time or moisture has entered inside
the machine, be sure to measure the insulation resistance. If resistance is lower than 1 MΩ ,
i t could cause an electrical leakage or fire. Dry the generator with compressed air until the
resistance exceeds 1 MΩ p r i o r to operating.
Since the generator insulation may drop when moisture, oil vapor, and dust are stuck,
always keep the machine clean.
Since sealed type ball bearings are used, supplying grease is not necessary.
(Procedure) (Megger tester required)
① Remove the load side cable from the output terminal
board.
② Remove the cable between the terminal “N” and
terminal “G” which are connected on the back of the
output terminal plate.
③ Remove the AVR connector inside the generator
control panel.
④ Switch ON the three-phase breaker, measure each
insulation resistance between the terminals L1. L2.
L3 terminal and bonnet.
⑤ Insulation resistance when measured with a 500 V
megger tester must be above 1 MΩ.
⑥ After finishing the measurement of insulation
resistance, re-connect the cable between the
terminal "N" and terminal "G".
After making sure that the insulation resistance of the
generator is higher than 1 MΩ, be sure to re-connect
the cable between the terminal "N" and terminal "G"
just as it was originally connected.If it is left
disconnected, the grounding becomes imperfect so that
it could cause electric shock.
SDG25S
A040195
SDG25S
H990311
SDG45S/60S/75S/100S
H990312