connecting the breaker from all power sources, per- form the following procedure:

1.Check that all phase sensors are the same type (current range).

2.Verify that the tap settings on all three phase sen- sors are identical.

3.Verify that the wiring harness connections to the sensors have the proper polarity (white lead to common, black lead to tap), as shown in the cabling diagram in Figure 36.

4.On ground fault breakers serving four-wire loads, check that the neutral sensor is properly con- nected, as indicated in Figure 36. In particular, check the following:

a.Verify that the neutral sensor has the same rat- ing and tap setting as the phase sensors.

b.Verify continuity between the neutral sensor and its equipment-mounted secondary discon- nect block. Also check for continuity from the breaker-mounted neutral secondary discon- nect block through to the trip unit wiring har- ness connector.

c.If the breaker’s lower studs connect to the power source, then the neutral sensor must have its load end connected to the source.

d.Verify that the neutral conductor is carrying only the neutral current associated with the breaker’s load current (the neutral is not shared with other loads).

5.If the preceding steps fail to identify the problem, then measure the sensor resistances. The appro- priate values are listed in Table 2. Since the phase and neutral sensors are electrically identical, their resistances should agree closely.

Breaker

CT Rating, A

Resistance, ohms

 

 

 

 

300

20–24

 

400

27–32

AK-50

600

42–50

AKS-50

800

58–68

 

1200

93–109

 

1600

130–154

 

1200

20–24

AK-75

1600

28–34

2000

37–44

 

 

3000

61–72

 

1600

36–43

AK-100

2000

47–55

3000

75–88

 

 

4000

108–127

Table 2. CT resistance values.

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Image 24
GE AK-50 installation instructions