Brochure

ManualsBrandsSquare D ManualsContactorsFront Mount Normally Open/Normally Closed Auxiliary Contact

GV2, GV3, and GV7 Manual Motor Starters, Controllers, and Protectors

Selection

6/2010

Selection

Fuse and Circuit Breaker Selection

When selecting the proper upstream short circuit protection for Group Motor installations, you must

apply the specific rules of the National Electrical Code (NEC) for Group Motor installations. To help

clarify this process, below are examples of how to choose the correct GV manual starter and the

proper size short circuit protection for an application. These examples illustrate the most common

applications of GV manual starters with upstream short circuit protection in a Group Motor installation.

Refer to NEC section 430-53C and section 430-53D for proper conductor ampacity selection.

NOTE: The examples below show full-load ampere (FLA) ratings that may not be typical. Use the

motor nameplate data to determine actual values.

Example 1: Eight motors with the sizes shown in Table 45 are installed on a conveying system. Time-delay fuses

are used.

In accordance with NEC section 430-52, section 430-53, and table 430-152, the time-delay fuse must

be sized as follows:

175% FLA for largest motor + sum of FLAs for all other motors

⇒ (1.75 x 7.6) + (2 x 4.8) + (5 x 3.4) = 39.9 A

NEC 430-52 allows use of the next largest standard-size fuse—which in this case is 40 A. If nuisance

tripping is a problem with this fuse selection, NEC does allow 225% of the largest motor FLA to be

used in lieu of 175% when calculating the size. In this case, the calculation is as follows (the next

largest standard fuse size in this case is 45 A):

(2.25 x 7.6) + (2 x 4.8) + (5 x 3.4) = 43.7 A

Example 2: Ten motors with the sizes shown in Table 46 are installed on a packaging machine. Choose the proper

size inverse-time circuit breaker for this application.

In accordance with NEC section 430-52, section 430-53, and NEC table 430-152, the inverse-time

circuit breaker must be sized as follows (the next largest standard-size inverse-time circuit breaker

is 90 A):

250% FLA for largest motor + sum of FLAs for all other motors

⇒ (2.5 x 14) + 14 +7.6 + (2 x 4.8) + (5 x 3.4) = 83.2 A

If nuisance tripping is a problem, the NEC allows for inverse-time circuit breaker sizes that “shall in no

case exceed 400% for full-load currents of 100 amps or less, or 300% for full-load current greater than

100 amps.” In this case, the calculation is as follows (the next largest standard inverse-time circuit

breaker size in this case is 110 A):

(4.0 x 14) + 14 +7.6 + (2 x 4.8) + (5 x 3.4) = 104.2 A

Disconnect

Fuse or

Circuit Breake

GV2 Manual Motor Starter

TeSys D or TeSys K

Contactor

Motor

Table 45: Example 1—Motor Sizes

Motor Quantity Rating (hp) Voltage FLA Starter Selected

154607.6GV2ME14

234604.8GV2ME10

524603.4GV2ME08

Table 46: Example 2——Motor Sizes

Motor Quantity Rating (hp) Voltage FLA

2 10 460 14

1 5 460 7.6

2 3 460 4.8

5 2 460 3.4