SJ700-2 Instruction Manual NT204DX - Hitachi America, Ltd.
SJ700-2 Instruction Manual NT204DX - Hitachi America, Ltd.
SJ700-2 Instruction Manual NT204DX - Hitachi America, Ltd.
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Chapter 6 Maintenance and Inspection<br />
6.5 Method of Checking the Inverter and Converter Circuits<br />
You can check the quality of the inverter and converter circuits by using a tester.<br />
(Preparation)<br />
1) Remove the external power supply cables from terminals R, T, and T, the motor cables from terminals<br />
U, V, and W, and the regenerative braking resistor cables from terminals P and RB.<br />
2) Prepare a tester. (Use the 1Ω-measuring range.)<br />
(Checking method)<br />
Measure the current conduction at each of the inverter's main circuit terminals R, S, T, U, V, W, RB, P, and<br />
N while switching the tester polarity alternately.<br />
Note 1:<br />
Note 2:<br />
Note 3:<br />
Before checking the circuits, measure the voltage across terminals P and N with the tester in DC<br />
voltage range mode to confirm that the smoothing capacitor has fully discharged electricity.<br />
When the measured terminal is nonconductive, the tester reads a nearly infinite resistance. The<br />
tester may not read the infinite resistance if the measured terminal flows a current momentarily<br />
under the influence of the smoothing capacitor.<br />
When the measured terminal is conductive, the tester reading is several ohms to several tens of<br />
ohms. The measured values may vary slightly, depending on the types of circuit devices and<br />
tester. However, if the values measured at the terminals are almost the same, the inverter and<br />
converter circuits have adequate quality.<br />
Only inverter models with capacity of 22 kW or less have the BRD circuit.<br />
Converter circuit<br />
Inverter circuit<br />
BRD circuit<br />
D1<br />
D2<br />
D3<br />
D4<br />
D5<br />
D6<br />
TR1<br />
TR2<br />
TR3<br />
TR4<br />
TR5<br />
TR6<br />
TR7<br />
Tester polarity<br />
⊕ (red) (black)<br />
Measurement result<br />
R PD Nonconductive<br />
PD R Conductive<br />
S PD Nonconductive<br />
PD S Conductive<br />
T PD Nonconductive<br />
PD T Conductive<br />
R N Conductive<br />
N R Nonconductive<br />
S N Conductive<br />
N S Nonconductive<br />
T N Conductive<br />
N T Nonconductive<br />
U P Nonconductive<br />
P U Conductive<br />
V P Nonconductive<br />
P V Conductive<br />
W P Nonconductive<br />
P W Conductive<br />
U N Conductive<br />
N U Nonconductive<br />
V N Conductive<br />
N V Nonconductive<br />
W N Conductive<br />
N W Nonconductive<br />
RB P Nonconductive<br />
P RB Conductive<br />
RB N Nonconductive<br />
N RV Nonconductive<br />
BRD circuit<br />
PD P RB<br />
Converter circuit<br />
D1 D2 D3<br />
R<br />
S<br />
C+<br />
T<br />
TR7<br />
D4 D5 D6<br />
N<br />
Inverter circuit<br />
TR1 TR2 TR3<br />
TR4 TR5 TR6<br />
U<br />
V<br />
W<br />
6 - 4
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