Mag-Gard™ Motor Circuit Protector
Class 680, 685
Mag-Gard Motor Circuit Protector
Instantaneous trip magnetic only circuit breakers have a single adjustment which simultaneously sets the magnetic trip level of each individual pole. Mag-Gard circuit breakers comply with NEC® requirements for providing motor circuit protection when installed as part of a UL Listed combination controller having motor overload protection. Interrupting ratings are established for these UL Recognized Components only when they are used in combination with motor starters with properly sized overload relays and contactors.
Mag-Gard circuit breakers will accept the same lugs and accessories as equivalent thermal-magnetic circuit breakers.
Magnetic-Only GJL Circuit Breakers, 400 A, 600 Vac, 50/60 Hz [1]
|
Ampere Rating |
Adjustable [2]
|
Cat. No. |
|
|---|---|---|---|
|
GJL [3] |
3 |
9–33 A |
|
|
7 |
21–77 A |
||
|
15 |
45–165 A |
||
|
30 |
90–330 A |
||
|
50 |
150–550 A |
||
|
75 |
225–825 A |
||
note
GJL MCP Selection
|
|
Adjustable instantaneous-trip circuit breakers are intended for
use in combination with motor starters with overload relays for the
protection of motor circuits from short circuits. Other specific applications
include rectifiers and resistance welders. These circuit breakers
contain a magnetic trip element in each pole with the trip point adjustable
from the front. Interrupting ratings are determined by testing the
instantaneous-trip circuit breakers in combination with a contactor
and overload relay.
Select instantaneous-trip
circuit breakers using the selection table below.
This selection table is suitable for motors, other than NEMA Design E, with locked-rotor indicating code letters per NEC® Table 430.7 (b).
Locked-Rotor Indicating Codes
|
Horsepower |
Motor Code letter |
|---|---|
|
1/2 or less 3/4 to 1-1/2 2 to 3 5 to 25 30 to 125 150 or more |
A–L A–K A–J A–H A–G A–F |
-
For other motors order a special thermal-magnetic circuit breaker with magnetic trip settings for the specific motor— specify motor horsepower, voltage, frequency, full-load current and code letter or locked rotor current.
-
Determine motor hp rating from the motor nameplate.
-
Refer to the tables and select an instantaneous-trip circuit breaker with an ampere rating recommended for the hp and voltage involved.
-
Select an adjustable trip setting of at least 800%, not to exceed 1300%, of the motor full-load amperes (FLA) for other than Design E motors. For Design E motors, select an adjustable trip setting of at least 1100% not to exceed 1700% of FLA.
-
The NEC 1300% maximum setting may be inadequate for instantaneous-trip circuit breakers to withstand current surges typical of the magnetization current of autotransformer type reduced voltage starters, or open transition wye-delta starters during transfer from “start” to “run”, constant hp multi-speed motors, and motors labeled “high efficiency”. Select thermal-magnetic circuit breakers from Digest Section 7 for those applications.
-
Part-winding motors, per NEC 430.3, should have two circuit breakers selected from the above at not more than one half the allowable trip setting for the horsepower rating. The two circuit breakers should operate simultaneously as a disconnecting means per NEC 430.103.
-
Based on NEC 430.52 and NEC Table 430.150. See Digest Section 7 for a available Adjustable Instantaneous-Trip Circuit Breakers.
GJL MCP Selection Table
GJL Adjustable Instantaneous-Trip Circuit Breakers for Single Motor Circuit Protection
|
Hp Ratings of Induction
Type Squirrel-Cage and Wound Rotor Motors |
Full Load Amperes [4] |
GJL Family |
Magnetic Trip Settings [5] |
||||
|---|---|---|---|---|---|---|---|
|
200 Vac |
230 Vac |
460 Vac |
575 Vac |
MIN |
MAX |
||
|
— |
— |
— |
1/2 |
0.8 |
1100% |
4100% |
|
|
— |
— |
1/2 |
— |
1 |
900% |
3300% |
|
|
— |
— |
— |
3/4 |
1.1 |
800% |
3000% |
|
|
— |
— |
3/4 |
— |
1.4 |
600% |
2400% |
|
|
— |
— |
1 |
— |
1.8 |
500% |
1800% |
|
|
— |
1/2 |
— |
— |
2 |
500% |
1700% |
|
|
— |
|
|
1-1/2 |
2.1 |
400% |
1600% |
|
|
1/2 |
— |
|
— |
2.3 |
400% |
1400% |
|
|
— |
— |
1-1/2 |
— |
2.6 |
300% |
1300% |
|
|
— |
— |
— |
2 |
2.7 |
300% |
1200% |
|
|
— |
3/4 |
— |
— |
2.8 |
300% |
1200% |
|
|
3/4 |
— |
— |
— |
3.2 |
700% |
2400% |
|
|
— |
— |
2 |
— |
3.4 |
600% |
2300% |
|
|
— |
1 |
— |
— |
3.6 |
600% |
2100% |
|
|
— |
— |
— |
3 |
3.9 |
500% |
2000% |
|
|
1 |
— |
— |
— |
4.1 |
500% |
1900% |
|
|
— |
— |
3 |
— |
4.8 |
400% |
1600% |
|
|
— |
1-1/2 |
— |
— |
5.2 |
400% |
1500% |
|
|
1-1/2 |
— |
— |
— |
6 |
400% |
1300% |
|
|
— |
— |
— |
5 |
6.1 |
700% |
2700% |
|
|
— |
2 |
— |
— |
6.8 |
700% |
2400% |
|
|
— |
— |
5 |
— |
7.6 |
600% |
2200% |
|
|
2 |
— |
— |
— |
7.8 |
600% |
2100% |
|
|
— |
— |
— |
7-1/2 |
9 |
500% |
1800% |
|
|
— |
3 |
— |
— |
9.6 |
500% |
1700% |
|
|
3 |
— |
7-1/2 |
10 |
11 |
400% |
1500% |
|
|
— |
— |
10 |
— |
14 |
600% |
2400% |
|
|
— |
5 |
— |
— |
15.2 |
600% |
2200% |
|
|
— |
— |
— |
1 |
17 |
500% |
1900% |
|
|
5 |
— |
— |
— |
17.5 |
500% |
1900% |
|
|
— |
— |
15 |
— |
21 |
400% |
1600% |
|
|
— |
7-1/2 |
— |
20 |
22 |
400% |
1500% |
|
|
7-1/2 |
— |
— |
— |
25.3 |
400% |
1300% |
|
|
— |
— |
20 |
25 |
27 |
600% |
2000% |
|
|
— |
10 |
— |
— |
28 |
500% |
2000% |
|
|
— |
— |
— |
30 |
32 |
500% |
1700% |
|
|
10 |
— |
— |
— |
32.2 |
500% |
1700% |
|
|
— |
— |
25 |
— |
34 |
400% |
1600% |
|
|
— |
— |
30 |
— |
40 |
400% |
1400% |
|
|
— |
— |
— |
40 |
41 |
400% |
1300% |
|
|
— |
15 |
— |
— |
42 |
400% |
1300% |
|
|
15 |
— |
— |
— |
48.3 |
500% |
1700% |
|
|
— |
— |
40 |
50 |
52 |
400% |
1600% |
|
|
— |
20 |
— |
— |
54 |
400% |
1500% |
|
|
20 |
— |
— |
60 |
62 |
400% |
1300% |
|
|
— |
— |
50 |
— |
65 |
300% |
1300% |
|