DEH–40029 Installation Instructions
ProTrip™ Conversion Kits
g
For I-T-E
K-1600 Low-Voltage Power Circuit
Breakers
INTRODUCTION
GE Conversion Kits are designed for upgrading existing
I-T-E low-voltage power circuit breakers, rather than
replacing the entire breaker. The Conversion Kits include
ProTrip™ Trip Units, the latest technological advance in
GE trip systems.
ProTrip Conversion Kits are designed and tested to
conform to ANSI Standard C37.59, allowing the retrofitter
to properly install the kit and acceptance test the breaker.
This publication covers installation of ProTrip Conversion
Kits on I-T-E® Types K-225, K-600, K-800, and K-1600
low-voltage power circuit breakers. Each Conversion Kit
contains all the components needed to convert from the
existing I-T-E electromechanical trip system.
®
Types K-225, K-600, K-800,
TABLE OF CONTENTS
SECTION 1. GENERAL INFORMATION............................................................................................................4
SECTION 2. BEFORE INSTALLATION..............................................................................................................4
SECTION 3. DISASSEMBLING THE BREAKER
I-T-E 225–800 Ampere Breakers............................................................................................................5
I-T-E 1600 Ampere Breakers..................................................................................................................6
SECTION 4. INSTALLING THE CONVERSION KIT
Installing Phase Sensors (CTs) ..............................................................................................................9
I-T-E 225–800 Ampere Breakers...............................................................................................9
I-T-E 1600 Ampere Red Frame Breakers Only.......................................................................11
I-T-E 1600 Ampere Black Frame Breakers Only.....................................................................13
Installing the Flux Shifter.......................................................................................................................14
Flux Shifter Adjustment.........................................................................................................................15
Mounting the Trip Unit Bracket .............................................................................................................16
Installing the Trip Unit ...........................................................................................................................17
Connecting the Trip Unit Wiring Harness .............................................................................................18
Configuring the Trip Unit.......................................................................................................................18
SECTION 5. FOUR-WIRE GROUND FAULT OPTION................................................................................19
SECTION 6. TESTING AND TROUBLE-SHOOTING
Testing ..................................................................................................................................................21
Trouble-Shooting...................................................................................................................................21
Nuisance Tripping on Ground Fault-Equipped Breakers.........................................................21
2
LIST OF FIGURES
1. Removing the insulated housing on a K-225, K-600, or K-800 breaker. .........................................................5
2. Trip unit housing removed, 225–800 A breaker s............................................................................................. 5
3. Drilling out the screws holding the trip units to the housing, 225–800 A breakers..........................................6
4. Bolts to be removed from the load stabs, 225–800 A breakers.......................................................................6
5. Removing the draw-out contact block on a K-1600 breaker............................................................................6
6. Removing the trip unit housings on a K-1600 breaker.....................................................................................7
7. Contact arm connections, 1600 A breaker.......................................................................................................7
8. Electromechanical trip unit disassembly, 1600 A breaker...............................................................................7
9. Trip unit housing, 1600 A breaker....................................................................................................................8
10. Installing shims on red frame 225–800 A breakers. ........................................................................................9
11. Copper load terminal installed, 225–800 A breakers....................................................................................... 9
12. Installing a CT assembly., 225–800 A breakers. .............................................................................................9
13. Converted trip unit housing, 225–800 A breakers............................................................................................9
14. Installed CT assemblies, 225–800 A breakers. ............................................................................................. 10
15. Tightening the CT assembly bolts, 225–800 A breakers...............................................................................10
16. Terminal assembly for K-1600 red frame breaker. ........................................................................................ 11
17. CT assembly for K-1600 red frame breaker...................................................................................................11
18. C-shaped barrier modification, 1600 A breakers. .......................................................................................... 12
19. Reassembled 1600 A breaker........................................................................................................................12
20. Terminal assembly, 1600 A black frame breakers......................................................................................... 13
21. CT assembly, 1600 A black frame breakers..................................................................................................13
22. Flux shifter installation, 225–800 A breakers.................................................................................................14
23. Flux shifter installation, 1600 A breakers. ......................................................................................................14
24. Reset linkage assembly. ................................................................................................................................14
25. Flux shifter adjustment................................................................................................................................... 15
26. Removing the top cover screws.....................................................................................................................16
27. Trip unit bracket and insulating barrier assembly.......................................................................................... 16
28. Trip unit bracket attached to the breaker. ......................................................................................................16
29. Attaching the trip unit to the mounting plate...................................................................................................17
30. Harness connector attached to the trip unit. ..................................................................................................17
31. Trip unit mounted on the breaker...................................................................................................................17
32. Optional trip unit mounting position................................................................................................................17
33. Trip unit wiring harness installation................................................................................................................ 18
34. Neutral sensor outline for K-225 and K-600 breakers...................................................................................19
35. Neutral sensor outline for K-800 and K-1600 breakers.................................................................................20
36. Cabling diagram for ProTrip™ trip units with ground fault on four-wire loads...............................................23
3
SECTION 1. GENERAL INFORMATION
SECTION 2. BEFORE INSTALLATION
GE Conversion Kit installation is straightforward, but
does require careful workmanship and attention to these
instructions. Familiarity with the breaker is highly
desirable. The general approach is to first remove the
existing trip devices from the breaker, then install the
ProTrip components. Following this procedure, the
converted breaker is performance tested before it is
returned to service.
The majority of trip unit kit installations do not require any
customized assembly work. However, some conversions
may involve unusual mounting conditions or accessory
combinations that require minor modifications and/or
relocation of components. In most instances, this
supplementary work can be done on site.
In preparation for the conversion, the installer should
verify that the appropriate current sensors and trip unit
have been furnished. Note that all ProTrip trip units
supplied with conversion kits are equipped with longtime, short-time, instantaneous, and defeatable ground
fault (LSIGX) trip functions. The installer should be aware
of how these functions will affect his application before
installing the conversion kit.
Whenever a ProTrip kit is installed on a breaker with a
four-wire system, an associated neutral sensor (CT) is
required for separate mounting in the equipment. Ensure
that retrofitted breakers are applied within their shortcircuit ratings.
As a service-related consideration, the installation of a
ProTrip kit provides an excellent opportunity to perform
normal maintenance on the breaker, particularly when
the front and back frames are separated. Such
procedures are described in the installation and
maintenance manuals supplied with the breaker and
equipment.
Before starting any work, turn off and lock out all power
sources leading to the breaker, both primary and
secondary. Remove the breaker to a clean, well-lighted
work area.
WARNING: Low-voltage power circuit breakers use
high-speed, stored-energy spring operating
mechanisms. The breakers and their enclosures
contain interlocks and safety features intended to
provide safe, proper operating sequences. For
maximum personnel protection during installation,
operation, and maintenance of these breakers, the
following procedures must be followed. Failure to follow
these procedures may result in personal injury or
property damage.
• Only qualified persons, as defined in the National
Electrical Code, who are familiar with the installation
and maintenance of low-voltage power circuit
breakers and switchgear assemblies, should
perform any work on these breakers.
• Completely read and understand all instructions
before attempting any breaker installation,
operation, maintenance, or modification.
• Turn off and lock out the power source feeding the
breaker before attempting any installation,
maintenance, or modification. Follow all lock-out
and tag-out rules of the National Electrical Code and
all other applicable codes.
• Do not work on a closed breaker or a breaker with
the closing springs charged. Trip an OPEN breaker
and be sure the stored-energy springs are
discharged, thus removing the possibility that the
breaker may trip OPEN or the closing springs
discharge and cause injury.
• Trip the breaker OPEN, then remove the breaker to
a well-lighted work area before beginning work.
• Do not perform any maintenance that includes
breaker charging, closing, tripping, or any other
function that could cause significant movement of a
draw-out breaker while it is on the draw-out
extension rails.
• Do not leave the breaker in an intermediate position
in the switchgear compartment. Always leave it in
the CONNECTED, TEST, or DISCONNECTED
position. Failure to do so could lead to improper
positioning of the breaker and flashback.
4
SECTION 3. DISASSEMBLING THE
BREAKER
I-T-E K series breaker frames need not be separated
front and back for installation of the Conversion Kit. The
general procedure is to remove and disassemble the trip
unit housing, then install the kit.
First, remove the breaker to a clean, well-lighted work
bench and place it in the upright position, so that both the
front and back are easily accessible.
I-T-E 225–800 Ampere Breakers
The electromechanical trip units are contained in a
common, insulated housing, as shown in Figure 1. Use
the following procedure to remove the trip units.
1. Remove the five Philips-head screws holding the trip
unit housing in place at the rear of the breaker. Save
the hardware for later reinstallation.
NOTE: On some I-T-E breakers, the load-side draw-out
fingers must also be removed.
2. Remove and discard the two Philips-head screws
mounting the trip unit to the contact arm on each
phase, as shown in Figure 1.
3. Remove the trip unit housing assembly from the rear
of the breaker, as shown in Figure 2.
Figure 2. Trip unit housing removed, 225–800 A
breakers.
Figure 1. Removing the insulated housing on a K-225, K-
600, or K-800 breaker.
5
4. Carefully drill out the four #10-32 screws on each
phase that hold the trip units to the housing, as
shown in Figure 3.
3
-16 x 2" bolt, nut, and lock
5. Remove and save the
/8
washer holding the trip unit to the bus on each
phase, as shown in Figure 4. The trip units can be
removed and discarded. The breaker is now ready
for conversion.
I-T-E 1600 Ampere Breakers
On I-T-E 1600 ampere breakers, each electromechanical
trip unit is contained in its own housing.
1. On draw-out breakers with electrical operators,
remove the four screws holding the draw-out contact
block assembly to the back frame, as shown in
Figure 5. Lift off the contact block assembly. Save
the hardware for later reinstallation.
2. Remove the two top and two bottom Philips-head
screws at the breaker rear holding each insulated trip
unit housing to the breaker frame, as shown in Figure
6. Save the hardware for later reinstallation.
NOTE: On some I-T-E breakers, the load-side draw-out
fingers must also be removed.
Figure 4. Bolts to be removed from the load stabs, 225–
800 A breakers.
Figure 3. Drilling out the screws holding the trip units to
the housing, 225–800 A breakers.
Figure 5. Removing the draw-out contact block on a K-
1600 breaker.
6
Figure 6. Removing the trip unit housings on a K-1600
breaker.
3. Remove and discard the four Philips-head screws
above the load terminals that connect each trip unit
to the contact arm, as shown in Figure 7. The trip unit
assemblies can be removed by pulling them out of
the rear of the breaker frame.
4. Carefully drill out the four #10-32 screws holding
each trip unit in its housing, as shown in Figure 8.
5. Remove and save the two Philips-head screws that
hold the copper terminal extensions beneath the load
terminals of each trip unit housing, as shown in
Figure 8.
6. Remove and discard the hardware holding each
copper load terminal to the metal mounting brackets.
Separate each trip unit from its housing. Discard the
trip units and save the insulated housing and
mounting brackets, shown in Figure 9.
Figure 7. Contact arm connections, 1600 A breaker.
Figure 8. Electromechanical trip unit disassembly, 1600
A breaker.
7
Figure 9. Trip unit housing, 1600 A breaker.
8
SECTION 4. INSTALLING THE
CONVERSION KIT
Installing Phase Sensors (CTs)
I-T-E 225–800 Ampere Breakers
1. On red insulated-frame breakers only, place the
0.062" alignment shim between the four mounting
holes on the trip unit housing, as shown in Figure 10.
2. On all breakers, mount the new copper load
terminals to the trip unit housing with the four #10-32
1
/4" screws, nuts, and plain and lock washers
x 1
supplied for each phase. At the top of each bus
assembly, reinstall the
previously in step 5 of Section 3, I-T-E 225–800
Ampere Breakers, as shown in Figure 11.
3. Place each CT, one at a time, on the phase bus post.
Place an insulating barrier over the end of the bus
post and mount the assembly to load terminal, as
shown in Figure 12. Insert the
lock and flat washers and finger tighten. Figure 13
shows the completed installation.
3
/8-16 x 2" bolt saved
5
/16-18 x 1" bolt with
Figure 11. Copper load terminal installed, 225–800 A
breakers.
Figure 10. Installing shims on red frame 225–800 A
breakers.
Figure 12. Installing a CT assembly., 225–800 A
breakers.
Figure 13. Converted trip unit housing, 225–800 A
breakers.
9
4. Reattach the converted trip unit housing to the rear of
the breaker with the five Philips-head screws
removed in step 1 of Section 3, as shown in Figure
14. Connect the copper load terminals to the contact
arms with two
5
/16-18 x 1" Philips-head screws, lock
washers, and flat washers for each. Finger tighten all
screws.
5. Tighten the bolts installed in step 2 to 200 in-lb, as
shown in Figure 15.
6. Tighten the two screws connecting the load terminals
to the contact arms in each phase, installed in step 4,
to 100 in-lb.
WARNING: Steps 5 and 6 ensure critical electrical
integrity connections. The designated bolts must be
correctly tightened for proper operation. Failure to
tighten these bolts properly will cause a breaker failure,
resulting in property damage and/or personal injury.
Figure 14. Installed CT assemblies, 225–800 A breakers.
Figure 15. Tightening the CT assembly bolts, 225–800 A
breakers.
10
I-T-E 1600 Ampere Red Frame Breakers Only
1. Attach the mounting brackets removed from the old
copper terminals in Section 3, step 6 of I-T-E 1600
Ampere Breakers, onto the insulated housings, using
the Philips-head screws removed in step 5, as shown
in Figure 16.
2. Attach a new copper load-terminal extension to each
insulated housing with the two
3
/8-16 x 1" bolts, lock
washers, and flat washers provided, as shown in
Figure 16.
1
3. Insert the two #10-32 x 1
/4" screws, with the lock
washers, flat washers, and nuts provided, through
the insulated housing, as shown in Figure 16.
4. Assemble a copper CT post, CT, and insulating
barrier onto each insulated housing. Insert and finger
tighten the
1
/2-13 x 11/2" bolt, with lock and flat
washers, into each CT post, as shown in Figure 17.
Figure 16. Terminal assembly for K-1600 red frame
breaker.
Figure 17. CT assembly for K-1600 red frame breaker.
11
5. Cut and remove all but 1/4" of the C-shaped projection on the insulating phase barrier inside the
breaker frame, to allow clearance of the CT bus post,
as shown in Figure 18.
6. Reattach the CT assembly housing to the breaker
frame, as shown in Figure 19. Use the four Philipshead screws removed in Section 3, step 2 of I-T-E
1600 Ampere Breaker.
5
7. Insert and finger tighten the four
/16-18 x 13/4"
screws, lock washers, and flat washer provided into
each contact arm above the load terminals, as shown
in Figure 19.
8. Tighten the CT bolts inserted in step 3 to 300 in-lb.
9. Tighten the four contact arm screws above each load
terminal to 100 in-lb.
WARNING: Steps 8 and 9 ensure critical electrical
integrity connections. The designated bolts must be
correctly tightened for proper operation. Failure to
tighten these bolts properly will cause a breaker failure,
resulting in property damage and/or personal injury.
Figure 18. C-shaped barrier modification, 1600 A
breakers, viewed from the bottom of the breaker.
Figure 19. Reassembled 1600 A breaker.
12
I-T-E 1600 Ampere Black Frame Breakers Only
1. Attach the mounting brackets removed from the old
copper terminals in Section 3, step 6 of I-T-E 1600
Ampere Breakers, onto the insulated housings, using
the Philips-head screws removed in step 5, as shown
in Figure 20.
2. Attach a new copper load-terminal extension to each
insulated housing with the two
3
/8-16 x 1" bolts, lock
washers, and flat washers provided, as shown in
Figure 20.
3. Place a CT and insulating barrier over the copper
post on each housing. Secure the assembly with the
top copper bus and the
1
/2-13 x 11/2" bolt, lock
washer, and flat washer provided, as shown in Figure
21. The bolt should be finger tight for now.
The remaining steps of this procedure are identical to
steps 5–9 for red frame breakers on the previous page.
Figure 20. Terminal assembly, 1600 A black frame
breakers.
Figure 21. CT assembly, 1600 A black frame breakers.
13
Installing the Flux Shifter
1. Carefully rotate the breaker onto its back so that the
bottom of the breaker is accessible.
NOTE: If the breaker has already been converted to
solid state trip devices, the existing trip actuator and
linkage must be removed and discarded.
2. Remove and retain the left front rack mounting bolt
on the breaker frame. The head of the bolt has a
radial slot cut into it. Slide the new flux shifter
assembly in through the bottom of the breaker, as
shown in Figure 22 for 225–800 A breakers and in
Figure 23 for 1600 A breakers. Align the bracket with
the hole in the frame from which the mounting bolt
was removed. Reinsert the mounting bolt through the
hole in the frame.
1
3. On 225–800 A breakers, insert the
and lock washer provided through the hole behind
the rack mounting bolt. The bolt is threaded into a
tapped hole in the mounting bracket, as shown in
Figure 22.
1
On 1600 A breakers, the
/4-20 x 1/2" bolt is inserted
through a hole in front of the rack mounting bolt, as
shown in Figure 23. On some older versions, a #8-32
1
/2" screw, lock washer, and nut are used instead
x
1
of the
/4-20 bolt.
4. Ensure that the reset arm linkage is on the inside of
the crossbar arm. Line up the hole in the reset arm
with the hole in the crossbar, as shown in Figure 24.
Insert the
1
/4" x 3/4" pin provided through the large
hole in the side of the breaker frame. Place the two
washers and the cotter pin provided on the other end
of the pin.
/4-20 x 1/2" bolt
Figure 22. Flux shifter installation, 225–800 A breakers.
NOTE: If an auxiliary switch is mounted on the left side
of the breaker, the auxiliary switch operating arm must
be modified. Drill out the pin that is connected to the
crossbar arm with a 0.257"-diameter drill. Place the end
of the link over the pin inserted through the crossbar
arm and reset link. Use only one washer and the cotter
pin.
Figure 23. Flux shifter installation, 1600 A breakers.
Figure 24. Reset linkage assembly.
14
Flux Shifter Adjustment
After the flux shifter has been installed, the following
adjustment must be made:
With the breaker upright in the CLOSED position, the gap
between the trip paddle and the flux shifter adjustment
screw, shown in Figure 25, should be
diameter gage or drill rod (not provided) may help to
measure the gap.
If adjustment is necessary, OPEN the breaker, then use
1
/4" wrench or nut driver to turn the adjustment screw.
a
To eliminate play in the trip paddle, gently push on the
trip paddle while adjusting the screw.
WARNING: Be extremely careful when working on a
CLOSED breaker. DO NOT reach your hands into the
mechanism while adjusting the flux shifter.
Optional Test – The flux shifter may be tested by closing
the breaker and applying a 9 Vdc power source to the
flux shifter leads (the red wire is positive). The breaker
should trip.
1
/32". A 1/32"-
Figure 25. Flux shifter adjustment.
15
Mounting the Trip Unit Bracket
1. Rotate the breaker to the upright position. Remove
and save the Philips-head screws and washers at the
front of the top cover, as shown in Figure 26.
2. Attach the insulating barrier to the mounting bracket
with the wire ties provided, as shown in Figure 27.
3. Attach the trip unit bracket and shield assembly to
the top cover with the screws and washers removed
in step 1, as shown in Figure 28. Be sure that the
insulating barrier is between the arc chutes and the
bracket.
Insulating
Barrier
Bracket
Figure 27. Trip unit bracket and insulating barrier
assembly.
Figure 26. Removing the top cover screws.
Figure 28. Trip unit bracket attached to the breaker.
16
Installing the Trip Unit
1. Place a lock washer and flat washer over each of the
three
through the mounting holes on the trip unit mounting
plate. From the rear of the plate, place a flat washer,
spacer, and O-ring over the screws, as shown in
Figure 29.
2. Remove the large screw from the rear of the trip unit.
Place the trip unit in position on the mounting plate,
with the 50-pin connector aligned with the opening in
the plate. Secure with the large screw, as shown in
Figure 29.
3. Insert the 50-pin female connector on the wiring
harness into the trip unit connector through the rear
of the mounting plate. Secure to the mounting plate
with the two small screws provided, as shown in
Figure 30.
4. Place the trip unit and mounting plate in position on
the support bracket mounted on the breaker. Secure
with the three mounting screws into the tapped holes
in the bracket, as shown in Figure 31.
Optional Mounting – If a large auxiliary switch is
mounted on the breaker, the trip unit can be mounted
horizontally on its bracket, as shown in Figure 32.
1
/4-20 x 13/8" screws provided and insert
Figure 30. Harness connector attached to the trip unit.
Figure 29. Attaching the trip unit to the mounting plate.
Figure 31. Trip unit mounted on the breaker.
Figure 32. Optional trip unit mounting position.
17
Connecting the Trip Unit Wiring Harness
1. Carefully rotate the breaker onto its back so that the
bottom of the breaker is accessible.
2. Run the wires comprising the trip unit wiring harness
along the front of the insulating barrier, then down to
the bottom of the breaker, as shown in Figure 33.
3. Join the four-pin connector on the trip unit harness to
the four-pin connector on the flux shifter, as shown in
Figure 33.
4. Connect the harness leads to the screw terminals on
each CT, as shown in Figure 33. The black wire (tap)
connects to the left terminal and the white wire
(common) to the right terminal.
5. Use the wire ties provided to tie the harness back
against the frame. The harness should be tied to the
holes in the fiber barriers at each CT. Ensure that the
wiring will not interfere with any moving parts.
Configuring the Trip Unit
See DEH-40034 for detailed instructions for setting up
ProTrip trip units.
Figure 33. Trip unit wiring harness installation.
18
SECTION 5. FOUR-WIRE GROUND
FAULT OPTION
The ground fault option for four-wire installations requires
the installation of an additional current sensor on the
neutral bus in the equipment. The sensor is connected to
the trip unit through the connector provided in the wiring
harness.
1. Mount the neutral sensor on the outgoing neutral
lead, normally in the bus or cable compartment in the
equipment. Figure 34 shows the outline of the neutral
sensor for K-225 and K-600 applications. Figure 35
shows the neutral sensor for K-800 and K-1600
applications.
2. Connect the neutral sensor wire harness to the
correct taps on the sensor. To maintain the same
polarity as the phase sensors, connect the white wire
to the common terminal, black to the tap.
3. Route the wires through the equipment and connect
to the two-pin connector on the trip unit wiring
harness. The wires should be tied to the breaker
frame in an easily accessible location. It may be
located with the communication harness.
Figure 34. Neutral sensor outline for K-225 and K-600 breakers.
19
Figure 35. Neutral sensor outline for K-800 and K-1600 breakers.
20
SECTION 6. TESTING AND TROUBLESHOOTING
WARNING: Do not change taps on the current sensors
or adjust the trip unit settings while the breaker is
carrying current. Failure to adhere to these instructions
will void all warranties.
Testing
Before installing a converted breaker back into service,
perform the following steps:
1. Verify that the trip unit is securely installed by
performing a continuity test on the CT wiring and the
trip unit.
a. Disconnect the black CT wires at each phase
sensor.
b. Check for continuity with a continuity tester or
VOM from the white lead of the phase A CT to the
white lead of the phase B CT.
c. Repeat this continuity test for the white leads of
the phase A and phase C CTs.
d. Measure the resistance across each phase
sensor and compare the values measured to the
values listed in Table 1.
e. Reconnect the black CT leads to all of the phase
sensors. Ensure that this is done before
continuing with performance testing of the
breaker.
CAUTION: In addition to the continuity test described in
Step 1 and before performance testing of the converted
breaker, each phase of the breaker should be primary
injected with a current level of about 10%, but no more
than 20%, of the CT rating.
WARNING: If the converted breaker is energized or
tested by primary injection with a sufficiently high test
current with a loose or open circuit between the CTs
and the trip unit, damage will occur to the trip unit, wire
harness, 50-pin trip unit connector, and CTs. Failure to
adhere to these instructions will void all warranties.
2. Check the insulation on the primary circuit with a
1,000-volt Meggar.
3. Measure the resistance across the line and load
terminals for each phase using a micro-ohmmeter or
millivolt tester. If the resistance differs considerably
from phase to phase, the electrical connections may
not be properly tightened or it could also indicate
improper contact wipe.
4. To verify that the breaker has been properly retro-
fitted, perform a primary injection test on each phase.
This test will check the CTs, bus, wiring harness, flux
shifter, and trip unit as a complete system.
a. A high-current, low-voltage power supply should
be connected across each line and load terminal
to simulate an overcurrent fault.
b. Set the long-time trip at 0.5 to minimize the
breaker stress.
c. When ground fault is installed, the test can be
performed by wiring two adjacent poles in series
or by using the GE Digital Test Kit, cat. no.
TVRMS2. This will prevent the breaker from
tripping because of an unbalanced current flow.
CAUTION: Do not attempt to use GE Test Kit cat. no.
TVTS1 or TVRMS on this trip unit.
Trouble-Shooting
When malfunctioning is suspected, first examine the
breaker and its power system for abnormal conditions
such as the following:
• The breaker is not tripping in response to overcurrent conditions or incipient ground faults.
• The breaker is remaining in a trip-free state because
of mechanical interference along its trip shaft.
• The shunt trip (if present) is activating improperly.
Nuisance Tripping on Ground Fault-Equipped
Breakers
When nuisance tripping occurs on breakers equipped
with ground fault trip, a probable cause is the existence
of a false ground signal. Each phase sensor is connected
to summing circuitry in the trip unit. Under no-fault
conditions on three-wire load circuits, the currents add to
zero and no ground signal is developed. This current
sum is zero only if all three sensors have the same
electrical characteristics. If one sensor differs from the
others (such as by a different rating or wrong tap setting),
the circuitry can produce an output sufficient to trip the
breaker. Similarly, a discontinuity between any sensor
and the trip unit can cause a false trip signal.
The sensors and their connections should be closely
examined if nuisance tripping is encountered on any
breaker whose ProTrip trip unit has previously
demonstrated satisfactory performance. After disconnecting the breaker from all power sources, perform
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 sensors
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 connected,
21
as indicated in Figure 36. In particular, check the
following:
a. Verify that the neutral sensor has the same rating
and tap setting as the phase sensors.
b. Verify continuity between the neutral sensor and
its equipment-mounted secondary disconnect
block. Also check for continuity from the breakermounted neutral secondary disconnect block
through to the trip unit wiring harness 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 appropriate values are listed in Table 1. Since the phase
and neutral sensors are electrically identical, their
resistances should agree closely.
CT Rating, A Resistance, ohms
Breaker
K-225
K-600
K-800
K-1600
150
225
225
600
150
400
800
800
1600
Table 1. CT resistance values.
9–12
14–18
14–18
40–50
9–12
27–32
58–79
58–79
130–154
22
Figure 36. Cabling diagram for ProTrip™ trip units with ground fault on four-wire loads.
23
These instructions do not cover all details or variations in equipment nor do they provide for every possible contingency
that may be met in connection with installation, operation, or maintenance. Should further information be desired or should
particular problems arise that are not covered sufficiently for the purchaser’s purposes, the matter should be referred to the
GE Company.
g
GE Industrial Systems
General Electric Company
41 Woodford Ave., Plainville, CT 06062
DEH40029 R03 0899 © 1999 General Electric Company
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