
B–63833EN/03
4. POWER SUPPLY CONNECTION
38
When the vertical axis exists, select the DC power supply that has a long voltage
hold time to decrease the amount of vertical axis falling during power–off
(including a power failure).
If the operating voltage drops to less than or equal to 21.6V, the CNC releases
servo activation. Therefore, when the hold time for 24 VDC during AC
power–off is too short, servo activation is released before the breaks are applied
because some peripheral circuit detects power–off. This may increase the
amount of vertical axis falling.
Generally, a power supply with sufficient power capacity tends to increase the
hold time during power–off.
The following circuit configurations are not recommended.
1 Circuit examples that cannot retain the output voltage at an
instantaneous interruption (the voltage reduces to 21.6 V or below)
Example 1
AC input
Rectifier
circuit
CNC unit
Example 2
AC input
Rectifier
circuit
CNC unit
NOTE
The rectifier circuit means a circuit using diodes for
full–wave rectification.
2 Circuit examples that exceed the output voltage specifications (21.6
V to 26.4 V) due to an abrupt load change
Example 1
AC input
Regulated
power
supply
CNC unit
Device with
remarkable
load fluc-
tuations
S Notes to take when the
vertical axis exists
S Circuit configurations
Forbidden