Allen-Bradley ArmorStart 290E User Manual page 186

Appendix A Applying More Than One ArmorStart LT Motor Controller in a Single Branch Circuit on Industrial Machinery
186
Figure 61 - ArmorStart LT NFPA 79 Multi-Motor Branch Circuit —
Conductor and Controller Protection
Electrical Supply -
480Y/277V
Available Fault Current
Sym. Amps RMS 9 KA
Disconnecting
Means
a
Fuses
45 A Max,
Branch short-circuit
CC, J or T
and ground-fault
protection device
d
Controller
ratings
further
restrict the
fuse
"Suitable for Motor Group Installation"
Max. Ratings
Sym. Amps RMS 5 KA 10 KA
Fuse 45A 45A*
* Type CC, J and T fuses only
Compare to
d
controller max
fuse ratings
Table 7.2.10.4
Conductor
Max
protection -
Fuse
60 A max,
AWG (A)
any class
- -
14 60
12 80
10 100
8 150
- -
7.2.10.4(2) -
"smallest
conductor in
the circuit"
= 14 AWG
Figure 62 - ArmorStart LT NFPA 79 Multi-Motor Branch Circuit Minimum Conductor Ampacity
Electrical Supply
c
Min Amp. = Min Amp. =
125% * 1.8 A 125% * 5.5 A
I1 =
1.8 A
½ HP
Bulletin
294
1.1 A
Min Amp. = Min Amp. =
125% * 1.1A 125% * 3.4 A
1/2 HP
FLC =
1.1 A**
Rockwell Automation Publication 290E-UM001B-EN-P - June 2012
½ HP 2 HP
Bulletin 294 Bulletin 294
a
Overload Overload
Class 10 Class 10
Nameplate* Nameplate*
b
Conductor
c
protection
"Smallest
Determine
conductor"
fuse class
and max
rating for
1/2 HP 2 HP
conductor
FLC = FLC =
protection
1.1 A** 3.4 A**
* Each controller is suitable for group installation with the same maximum ratings of fuse.
** Table 430.250 of NFPA 70-2011
Minimum Required Ampacity (MRA)
MRA = 1.25 * Max {controller input currents} + Sum {remaining controller input currents}
Controller input currents = {I1,I2,I3,I4,I5}
Max controller input current = I3 = I4, choose I3 as Max (either is ok)
MRA = 1.25 * I3 + (I1 + I2 + I4 + I5}
= 1.25 * 7.6 A + (1.8 A + 5.5 A + 7.6 A + 3.0 A) = 27.4 A
Combined Load Conductors
Min Amp. =
a
125% * 7.6 A 125% * 7.6 A
I2 = I3 =
5.5 A 7.6 A
2 HP 5 HP
Bulletin Bulletin
294 291
3.4 A 7.6 A
Min Amp. =
a
125% * 7.6 A 125% * 7.6 A
2 HP 5 HP
FLC = FLC =
3.4 A** 7.6 A**
** Table 430.250 of NFPA 70-2011
Combined Load Conductors
10 AWG
5 HP 5 HP 1 HP
Bulletin 291 Bulletin 290 Bulletin 294
Overload Overload Overload
Class 10/15/20 Class 10/15/20 Class 10
Nameplate* Nameplate* Nameplate*
5 HP 5 HP 1 HP
FLC = FLC = FLC =
7.6 A** 7.6 A** 2.1 A**
10 AWG
Min Amp. = Min Amp. =
b 125% * 3.0 A
I4 = I5 =
7.6 A 3.0 A
5 HP 1 HP
Bulletin Bulletin
290 294
7.6 A
Min Amp. = Min Amp. =
b
125% * 2.1 A
5 HP
1 HP
FLC =
FLC =
7.6 A**
2.1 A**
2.1 A