Allen-Bradley 1391B Series, Instruction Manual

Page: 62 / 82

Transformers and Shunt Regulators
Chapter 9
9-60
ATTENTION: Proper derating must be applied to the
manufacturers nominal resistor power ratings when using these
in external shunt configurations. Consult the resistor
manufacturer for recommended derating. Failure to comply
could result in personal injury and/or equipment damage from
an overheated resistor.
!
Shunt Fusing
Shunt regulator fusing is provided with all of the 1391B-ES controllers.
The fuse is in series with the resistor and used to protect the resistor against
short circuits. The shunt fuse is located on top of the controller near the
circuit breaker for 15 and 22.5A controllers. External resistors for 22.5A
and 45A controllers are supplied with a fuse which must be mounted
external to the controller (see Appendix A for mounting dimensions). Refer
to Table 9.C for further shunt fuse information.
Table 9.C
Shunt Fuse Information
Controller
Rating
15A
22.5A
22.5A
45A
Fuse Loca-
tion
Top Panel
Top Panel
External
External
Fuse Type
Buss KLM-10 or equivalent
Buss FNM-6.25 or equivalent
Buss KTK-15 or equivalent
Buss KLM-20 or equivalent
Important: Repeated overvoltage tripping can be an indication that the
shunt fuse has malfunctioned.