184 Rockwell Automation Publication 290E-UM001B-EN-P - June 2012
Appendix A Applying More Than One ArmorStart LT Motor Controller in a Single Branch Circuit on Industrial Machinery
The following text and Figure 60 provide an explanation of 7.2.10.4(1)
and (2). In the following, the text not relevant to Figure 58
is replaced
by ellipsis points (…). Then each individual requirement is underlined and
followed by an underlined letter in parentheses. This underlined letter in the
following text corresponds to the letter in Figure 60
.
“7.2.10.4 Two or more motors (a)
…and their control equipment (b) shall be
permitted to be connected to a single branch circuit (c) where short-circuit and
ground-fault protection is provided by a single inverse time circuit breaker or a
single set of fuses (d), provided the following conditions under (1) and…(2)…
are met:
(1) Each motor controller and overload device is… listed for group installation
with specified maximum branch-circuit protection (e) …
(2) The rating or setting of the branch short-circuit and ground-fault protection
device does not exceed the values in Table 7.2.10.4 for the smallest conductor
in the circuit.” (f )
Summarizing the requirements relevant to Figure 58: 7.2.10.4(1) and 7.2.10.4(2)
permit two or more ArmorStart LT motor controllers to be installed in a single
branch circuit provided (1) all the motor controllers are listed for group
installation, (2) the fuse does not exceed the maximum rating that Tab le 3 0
permits to protect the smallest conductor and (3) the fuse complies with the
maximum fuse ratings of all of the controllers.
Table 30 - Abbreviated Table 7.2.10.4
Table 7.2.10.4 Relationship Between Conductor Size and Maximum Rating or Setting of Short-Circuit
Protective Device for Power Circuits Group Installations
Conductor Size (AWG) Maximum Rating
Fuse or Inverse Time*
Circuit Breaker
(amperes)
……
……
14 60
12 80
10 100
8 150
6 200
……
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