2-10
Installation
Fast Acting
Current-limiting
Fuses
Short-circuit protection guidelines are provided in Appendix A of this
manual. Enhanced SCR protection may be obtained with the use of
fast acting current-limiting fuses. Table 2.C provides a listing of
fuses that are coordinated to protect the controller SCRs in the event
of a ground fault or short-circuit at the connected load. If SCR fusing
is not used, the controller power modules may be damaged and
require replacement. Supplementary SCR fusing, however, is not
required by the NFPA 70 (National Electric Code).
Table 2.C Recommended Fuses
Note: Fuse size listed is for 230V, 460V, or 575V.
①
Fuse manufacturer’s cross reference of the fuse Cat. Nos. listed here may not provide proper
coordination.
②
Two fuses per phase are required for these controller ratings.
SMC
Rating
Fuse Manufacturer Cat. No.
①
Bussman Shawmut Edison (Brush) Ferraz Littlefuse
24A
SPP-4F60
170M 3610-63
A70P70 XL70F080 A070F060 L70S60
35A
SPP-4F100
170M 3612-100
A70P100 XL70F125 A070F100 L70S100
54A
SPP-4F150
170M 3614-160
A70P200 XL70F200 A070F150 L70S150
97A
SPP-4F300
170M 3617-315
A70P300 XL70F300 A070F300 L70S300
135A
SPP-4F300
170M 3617-315
A70P300 XL70F300 A070F300 L70S300
180A
SPP-4F400
170M 3619-400
A70P400 XL70F400 A070F400 L70S400
240A
SPP-6F400
170M 5608-400
A70P500 XL70F500 A070F400 L70S400
360A
SPP-6F600
170M 5612-630
A70P800 XL70F600 A070F800 L70S600
500A
SPP-6F800
170M 6613-900
A70P1000 XL70F500
②
A070F800 L70S800
650A
SPP-6F800
170M 6613-900
A70P1000 XL70F500
②
A070F800 L70S500
720A
SPP-5F600
②
170M 5612-630
②
A70P1200 XL70F600
②
A070F800 L70S500
850A
SPP-7F1200
170M 6615-1100
A70P1000
②
— A070F1200 L70S800
1000A
SPP-6F800
②
170M 6613-900
②
A70P1000
②
— A070F1200 L70S800
!
!
ATTENTION: The fast acting current-limiting fuses
specified in Table 2.C may not provide branch circuit
protection. Branch circuit protection in accordance
with applicable electrical codes may require additional
fusing (or a circuit breaker) even though fast acting
current-limiting fuses are used.
ATTENTION: Applications requiring extended
acceleration times or high duty cycles may experience
nuisance tripping of the coordinated fast acting current-
limiting fuses. This type of fuse has a limited thermal
capacity that is less than that of the SCRs they are
designed to protect. This makes them susceptible to
thermal fatigue.
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