Hitachi L300P Series Service Manual page 33

5.5 How to check inverter & converter portion
Inverter and converter module can be checked by using a tester.
(Preparation)
(1)Disconnect all the connected wires and devices to the power terminals (R, S, T, U, V, W, P and RB).
(2)Tester is to be set as 1ohm range.
(How to check)
Check the ON condition of each point shown below.
(note 1) Be sure to discharge DC bus voltage beforehand, which should be checked by DC bus voltage.
(note 2) Normally, the resistance shows
In some cases resistance does not show
Resistance shows
Resistance values may not be completely the same due to the electrical device (IGBT chip, diode chip...) difference.
But we can regard the result is okay if all the data are nearly the same.
Tester polarity
(Red)
R
D1
PD
S
D2
PD
T
D3
PD
R
D4
N
S
D5
N
T
D6
N
U
TR1
P
V
TR3
P
W
TR5
P
U
TR4
N
V
TR6
N
W
TR2
N
RB
P
TR7
RB
N
A
A
K
THY
K
G
G
ON; Low resistance
OFF; High resistance
in case of OFF mode.
3ohm ~ 50ohm (depends on the tester voltage) in case of ON mode.
Measure
(Blk) ment
PD OFF
R ON
PD OFF
S ON
PD OFF
T ON
N ON
R
R OFF
N ON
S
S OFF
N ON
T OFF
T
P OFF
U ON
P OFF
V ON
P OFF
W ON
N ON
U OFF
N ON
V OFF
N ON
W OFF
P OFF
RB ON
N OFF
RB OFF
K OFF
G OFF
A OFF
G ON
A OFF
K ON
5- 4
due to the capacitance of DC bus capacitors.
PD
Converter
D1
D2 D3
THY
D5 D6
D4
Thyristor portion
A
P RB
Inverter
TR1
C+
TR7 TR4
BRD
N
K
G
TR3 TR5
U
V
W
TR6 TR2