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6-4 Branch-circuit protection (for control power supply)
6-4-1 Circuit protector
This breaker is used to switch the control power and to provide overload and short-circuit protection.
When connecting a circuit protector to the power input (L11 and L21) for the control circuit, use a product that
does not trip (incorrectly activate) by a rush current when the power is turned ON. A circuit protector with inertial
delay is available to prevent unnecessary tripping. Select the product to be used according to the machine
specifications.
The rush current and rush conductivity time differ according to the power impedance and power ON timing, so
select a product that does not trip even under the conditions listed in the following table.
Rush current: Ip=30A
(per 1 unit)
36.8%
When collectively protecting the control circuit power for multiple units, select a circuit protector that
POINT
satisfies the total sum of the rush current Ip.
The largest value is used for the rush conductivity time T.
6-4-2 Fuse protection
The fuse of branch-circuit protection must use UL class CC, J or T. In the selection, please consider rush current
and rush conductive time.
Connected total of unit
For continued protection against risk of fire, replace only with same type 600 V, 20 or 35 A
CAUTION
(UL CLASS CC) fuse.
Before replacing fuse, confirm all power controlling the drive system is shut-OFF. Be sure to look out
WARNING
the power source to prevent the power from being turned ON while maintenance is being performed.
I [A]
Rush conductivity time:
Time to reach 36.8% of rush current Ip,
equivalent to circuit protector operation characteristics
operation time.
Time
constant:
T = 9ms
Selection of branch-circuit protection fuse
Rated [V]
1 - 4
5 - 8
MDS-D-SVJ3/SPJ3 Series Specifications Manual
6-4 Branch-circuit protection (for control power supply)
t [ms]
Fuse (Class CC)
Current [A]
20
600
35
Wire Size
AWG
16 to 14
6 - 7
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