Yaskawa YASNAC PC NC Maintenance Manual - Manual (Page 72)

Chapter 4: Troubleshooting PC NC Maintenance Manual
4-51
AL-12:Main circuit low voltage
Error Contents The main circuit DC voltage became below the low voltage detection
level (149V) while driving.
Detection Methods Output to the control card formatting the main circuit DC voltage sig-
nal [VDET] by the gate driver (7CN-41).
Determine whether VDC is lower than the main circuit low voltage
detection level or that it is more than the main circuit low voltage
release level.
Main circuit low voltage detection level: 149V (200V class) and 298V
(400V class)
Main circuit low voltage release levels: 159V (200V class) and 318V
(400V class)
Cause and measures
Cause Measures
Converter selection is defective. Perform a proper selection (related to the servo capacity).
Reactor selection is defective. Perform a proper selection (corresponding to the converter
capacity).
Power supply voltage is low. Change the power supply voltage in the specification value by
transformer tap, etc.
Power supply open phase/power fail-
ure Check the voltage between input terminals.
Change the power supply voltage in the specification value by
transformer tap, etc.
Normalize the power supply.
Bus-bar (main circuit P, N) connection
is defective Confirm that there are no loose connections in the bus-bar.
Connector connection for main circuit
DC voltage detection is defective. Confirm that there are no loose connections in the main cir-
cuit DC voltage detection.
Control card fault Exchange unit (exchange control card)