Yaskawa P7B Drive Bypass - Manual (Page 203)

Diagnostic & Troubleshooting 6 - 23
Table 6.6 Main Circuit Test Procedure (Continued)
Check
Procedure
Input Diodes
(D1-D12 or Q1)
11. Place the positive (red) meter lead on terminal
⊕
1.
Place the negative (black) meter lead on terminal R/L1.
Expected reading is OL displayed.
12. Place the positive (red) meter lead on terminal
⊕
1.
Place the negative (black) meter lead on terminal S/L2.
Expected reading is OL displayed.
13. Place the positive (red) meter lead on terminal
⊕
1.
Place the negative (black) meter lead on terminal T/L3.
Expected reading is OL displayed.
Soft Charge Resistor Check
(R1, R2, 6PCB)
The soft charge resistor works in conjunction with the soft charge contactor to slowly charge
the DC bus capacitors to minimize the inrush current when power is applied to the Drive.
1. Conduct a visual inspection. Check for physical damage.
2. Set a digital multi-meter to the R x 1 scale.
3. If the resistor is damaged, the measured value will be infinite ohms.
Soft Charge Contactor
(K1)
The purpose of the soft charge contactor is to bypass the soft charge resistor after the DC bus
voltage has reached its normal operating level.
1. Conduct a visual inspection. Check for physical damage.
2. Set a digital multi-meter to the R x 1 scale.
3. On Drives with a board-mounted contactor, verify that each contact
resistance measures infinite ohms.
4. On Drives without a board-mounted contactor, press the plunger in, and verify that each
contact measures zero ohms.
5. On Drives without a board-mounted contactor, release the plunger, and verify that the
resistance is the ohmic value of the soft charge resistor.
6. On Drives with a board-mounted contactor, verify that the contactor coil measures about
300 ohms. The coil can be tested by applying the appropriate voltage to verify the con-
tacts change states.
7. On Drives without a board-mounted contactor, verify that the 230VAC contactor coil
measures about 175 ohms. The coil can be tested by applying the appropriate voltage to
verify the contacts change states.
8. On Drives without a board-mounted contactor, verify that the 24Vdc auxiliary coil
measures about 2.2M ohms. The coil can be tested by applying the appropriate voltage to
verify the contacts change states.
DC Bus Fuse
(F1)
The DC bus fuse is located in the negative portion of the DC Bus. The DC bus fuse is used to
protect the main circuit components if the output transistors short. If the DC bus fuse is open,
at least one of the output transistors has failed. When a transistor fails, there is a short
between the positive and negative portions of the DC Bus. The DC bus fuse does not protect
the transistors, but protects the rest of the main circuit from the high current present during a
short. Never replace the DC bus fuse without first checking all of the output transistors.
1. Set a digital multi-meter to the R x 1 scale.
2. Place one lead of the multi-meter on one side of the fuse and place the other lead of the
multi-meter on the other side of the fuse.
3. If the fuse is good, the measured value will be zero ohms.
If the fuse is bad, the measured value will be infinite ohms.