Cooper Power Systems GW Technical specifications

Serial No. 2415 and above
Service Information
Type GW
Maintenance Instructions S270-20-5
Sectionalizers
Serial No. 2415 and above

The instructions in this manual are not intended as a sub-
stitute for proper training or adequate experience in the
safe operation of the equipment described. Only compe-
tent technicians who are familiar with this equipment
should install, operate, and service it.
A competent technician has these qualifications:
• Is thoroughly familiar with these instructions.
• Is trained in industry-accepted high- and low-voltage
safe operating practices and procedures.
• Is trained and authorized to energize, de-energize,
clear, and ground power distribution equipment.
• Is trained in the care and use of protective equipment
such as flash clothing, safety glasses, face shield,
hard hat, rubber gloves, hotstick, etc.
Following is important safety information. For safe instal-
lation and operation of this equipment, be sure to read
and understand all cautions and warnings.
Safety Instructions
Following are general caution and warning statements
that apply to this equipment. Additional statements, relat-
ed to specific tasks and procedures, are located through-
out the manual.
SAFETY INFORMATION
WARNING: This equipment is not intended to
protect human life. Follow all locally approved pro-
cedures and safety practices when installing or operat-
ing this equipment. Failure to comply can result in
death, severe personal injury and equipment damage.
G102.1
!
DANGER: Hazardous voltage. Contact with
hazardous voltage will cause death or severe
personal injury. Follow all locally approved safety pro-
cedures when working around high voltage lines and
equipment. G103.3
!
WARNING: Before installing, operating, main-
taining, or testing this equipment, carefully read
and understand the contents of this manual. Improper
operation, handling or maintenance can result in death,
severe personal injury, and equipment damage. G101.0
!
WARNING: Power distribution equipment must
be properly selected for the intended application.
It must be installed and serviced by competent person-
nel who have been trained and understand proper safe-
ty procedures. These instructions are written for such
personnel and are not a substitute for adequate training
and experience in safety procedures. Failure to proper-
ly select, install, or maintain power distribution equip-
ment can result in death, severe personal injury, and
equipment damage. G122.2
!
SAFETY FOR LIFE
Cooper Power Systems products meet or exceed all applicable industry standards relating to product safety. We actively
promote safe practices in the use and maintenance of our products through our service literature, instructional training
programs, and the continuous efforts of all Cooper Power Systems employees involved in product design, manufacture,
marketing, and service.
We strongly urge that you always follow all locally approved safety procedures and safety instructions when working
around high voltage lines and equipment and support our “Safety For Life” mission.
!
SAFETY
FOR LIFE
!
SAFETY
FOR LIFE
This manual may contain four types of hazard
statements:
DANGER: Indicates an imminently haz-
ardous situation which, if not avoided, will
result in death or serious injury.
WARNING: Indicates a potentially hazardous
situation which, if not avoided, could result in
death or serious injury.
CAUTION: Indicates a potentially hazardous
situation which, if not avoided, may result in
minor or moderate injury.
CAUTION: Indicates a potentially hazardous situ-
ation which, if not avoided, may result in equip-
ment damage only.
!
!
Hazard Statement Definitions
!
2
Type GW Maintenance Instructions

S270-20-5
3
Figure 2.
Bi-stable actuator. 87908KMA
INTRODUCTION
Service Information S270-20-5 covers maintenance instruc-
tions for the Type GW electronically controlled three-phase
sectionalizer. It covers—in separate sections—a general
description of the unit, a detailed description of operation (both
electronic and mechanical), instructions for periodic inspection
and maintenance, testing and troubleshooting, and shop
repairs. In addition, service parts lists keyed to exploded-view
drawings of the various sectionalizer parts groups are included
in the back of this manual.
DESCRIPTION AND OPERATION
General
The sectionalizer is a self-contained, circuit-opening device
used in conjunction with source-side protective devices, such
as reclosers or reclosing circuit-breakers, to automatically iso-
late faulted sections of electrical distribution systems. The sec-
tionalizer senses current flow above a preset level, and when
the source-side protective device opens to deenergize the cir-
cuit, the sectionalizer counts the overcurrent interruption.
Depending upon the coordination scheme, the sectionalizer
will open during the first, second, or third open interval of the
fault interrupting device to isolate permanent faults and con-
fine outages to smaller sections of line.
The sectionalizer does not interrupt fault current but can be
closed into a faulted line. lt opens during the open interval of
the backup device. For this reason, it must always be used in
series with a fault-interrupting, backup protective reclosing
device. Also, it will forget counts that do not reach the counts-
to-open setting within the selected reset time due to clearing
of temporary faults.
When properly applied, the sectionalizer will respond to
downline fault currents that are interrupted by its backup
device. However, as with any other protective device, system
conditions may produce unexpected and unwanted sectional-
izer operation. Overcurrents interrupted by a downline device
is one cause for these occurrences, inrush current is another.
Count restraint and inrush current restraint features are built
into the sectionalizer control to block the sectionalizer’s
response to these system conditions.
A minimum of one-half amp of load current flowing through
any phase of the sectionalizer will block the generation of a
count pulse. This “count-restraint” feature prevents the sec-
tionalizer from counting overcurrents interrupted by downline
devices.
The sectionalizers are also equipped with an inrush-current
restraint feature which distinguishes between inrush currents
and fault currents. If it is determined that the overcurrent
through the sectionalizer is inrush current, the phase actuating
current level of the sectionalizer is raised by a multiple (X) for
a time (Y) after circuit energization. At the same time, ground
overcurrent protection is blocked entirely for a time (Z).
RATINGS
Operating Data
Phase-minimum-actuating 16, 24, 40, 56, 80,112,160
current (amps) 224, 256, 296, 320, 448,
640, 768, 896
Ground-minimum-actuating 3.5, 7, 16, 20, 28, 40, 56, 80,
current (amps) 112,160, 224, 320, 384
448, BLOCK
Number of counts to open 1, 2, 3
Count reset (seconds) 15, 30, 60, 120, 180
Phase actuating level multiplier X1, X2, X4, X6, X8, BLOCK
(inrush restraint)
Phase inrush reset (cycles) 5,10,15, 20
Ground inrush reset (seconds) 0.3, 0.7, 1.5, 3.0, 5.0
Basic Sectionalizer Ratings
Nominal voltage (kv) 34.5
Rated maximum voltage (kv) 38
Impulse withstand 1.2 x 50 microsecond wave
(BIL) (kv) 150
60 hertz withstand
Dry, 1 minute (kv) 70
Wet, 10 seconds (kv) 60
Continuous current rating (amps) 400
Rated symmetrical interrupting current (amps rms) 880
Rated making current, asymmetrical (amps rms) 15000
Short-time ratings (amps rms)
10-seconds symmetrical 3500
1-second symmetrical 10000
Momentary maximum, asymmetrical (amps rms) 1500
Creepage distance, standard bushing (in.) 23-1/2
DESCRIPTION OF OPEATION
All three sets of moving contacts are linked with bellcranks to a
common torque shaft connected to the electronically controlled
operating mechanism. The mechanism can also be operated
manually. Manual controls consist of the yellow pullring for trip-
ping and the red pullring for closing.
For automatic tripping, a bi-stable actuator trip mechanism is
operated from the electronic sensing-and-counting system.
Bistable actuation is provided by a permanent magnet-and-coil
assembly mounted on a springloaded frame and linkage
(Figure 2). When the sectionalizer is closed, the armature
below the trip rod is held against the core by the magnetic
force produced by the permanent magnet. In this state, a com-
pressed spring is trying to pull the trip shaft away from the
core. During the tripping operation, a silicon-controlled rectifier
connects charged capacitors across the coil of the magnetic
tripping assembly. The counterflux produced by the discharge
of the capacitors is sufficient to allow the spring to override the
magnetic force and operate the tripping circuit.

4
Type GW Maintenance Instructions
ELECTRONIC CONTROL CIRCUIT
The printed circuit board in the operator cabinet mounts the
electronic components of the control circuit (Figure 3). A func-
tional block diagram of the electronic circuitry is shown in
Figure4.
Current flowing through the sectionalizer is sensed by the
bushing-current transformers. Three transformers connected
in a wye configuration sense phase currents. Another three
bushing-current transformers connected in parallel sense the
ground (earth) or zero-sequence current. These signals are
rectified and are adjusted to the desired minimum-actuating
current level by the selection of the proper plug-in resistors.
To generate and register a count pulse, a current above the
preset-minimum-actuating level must be flowing through the
sectionalizer (downline fault) and this overcurrent must drop to
zero (fault interrupted by the backup protective device). The
pulse counter provides storage for up to three pulses.
Depending upon the counts-to-open setting, the tripping circuit
will turn on after one, two, or three count pulses have been
registered. When turned on, the tripping circuit completes the
discharge path for the trip-energy-storage capacitors through
the coil of the bi-stable actuator which, in turn, trips the sec-
tionalizer mechanism to open the sectionalizer contacts.
The pulse count reset will erase any stored pulse counts
whenever load current through the sectionalizer flows without
interruption for longer than the reset time programmed.
A count-restraint feature is built into the control of Type GW
sectionalizer to prevent the sectionalizer from counting fault
currents interrupted by a downline protective device. The cur-
rent restraint will block the generation of a count pulse as long
as at least one-half amp of load current is flowing through the
sectionalizer after the disappearance of fault current. Figure 5.
Typical connection diagram for three-wire control.
87905KMA
Figure 4.
Functional bolck diagram for sectionalizers.

S270-20-5
5
Figure 5.
Logic diagram for inrush-current restraint feature (both
phase and ground currents).
Figure 7.
Schematic diagram of trip operation.
Figure 6.
Schematic diagram of actuator mechanism with contacts closed.
ACTUATOR MECHANISM OPERTION
All three sets of moving contacts are linked to a common
shaft. To describe the mechanical operation of the GW sec-
tionalizer, a single set of contacts connected to a simplified
straight-line motion linkage is shown diagrammatically:
With the contacts closed, Figure 6, the opening spring is
held extended by the latched toggle mechanism. The trip
signal from the electronic control actuates the bi-stable actu-
ator assembly which acts upon the trip lever to break the
toggle latch. This action collapses the toggle to open the
contacts and place the mechanism in the condition shown in
Figure 7. Both the closing and opening springs are relaxed
The control is also equipped with an inrush-current
restraint feature which distinguishes between inrush current
and fault current bye logic circuit functionally diagrammed in
Figure 5. If an overcurrent is present through the sectionaliz-
er when the backup protective device opens (current is inter-
rupted), the overcurrent present upon reclosing is assumed
to be fault current and the sectionalizer control operates in
the normal manner as previously described. If, however,
there is no overcurrent detected by the sectionalizer when
the current is interrupted, the overcurrent present upon
reclosing is assumed to be inrush current. To prevent the
sectionalizer from counting this inrush current, the fault level
detector circuit is modified to raise the phase actuating level
by a multiple of 2X, 4X, 6X, or 8X the normal setting (or cur-
rent detection can be blocked entirely) for a time (Y) of
5,10,15, or 20
cycles after current flow through the sectional-
izer is restored. Upon expiration of this time, the sectionaliz-
er control returns to normal operating settings. At the same
time, ground overcurrent detection is blocked entirely for a
period (Z) of 0.3, 0.7, 1.5, 3, or 5 seconds after current flow
through the sectionalizer is restored.

6
Type GW Maintenance Instructions
Figure 8.
Schematic diagram of closing operation.
and the contacts remain open until closed manually. The open-
ing motion of the main torque shaft also resets the bi-stable
actuator assembly. Operating the closing pullring rotates the
ratchet-and-crank assembly clockwise to extend both springs
as shown in Figure 8. The motion of the crank arm also
extends the toggle members until they latch. A few more
degrees of ratchet travel will overtoggle the crank arm and
cause the extended closing spring to pull the mechanism
through the remainder of its travel to close the contacts. The
latched toggle and extended opening springs are carried along
with the contacts into the original closed position shown in
Figure 6. The mechanism is now set for another trip operation.
The contacts can be tripped open manually with another
pullring located underneath the operator mechanism housing.
The manual trip pullring acts on the trip lever to break the latch
and collapse the toggle.
MAINTENANCE
Frequency of Maintenance
Because sectionalizers are applied underwidely varying oper-
ating and climatic conditions, maintenance intervals are best
determined by the user based on actual operating experience.
However, to assure proper operation sectionalizers must be
routinely maintained; sectionalizers should be externally
inspected, the oil level should be checked and the dielectric
strength of the oil should be measured on a yearly basis. (See
steps 1, 2, 8 and 10 of “Periodic Inspection and Maintenance”
below.) Each periodic check should include at least the follow-
ing steps:
CAUTION: Never use volatile solutions, deter-
gents, or water-soluble cleaners.
!
WARNING: Continuous use of a sectionalizer,
without regualr routine inspection and repair, can
effect reliability. This could lead to equipment failure
and possible injury.
!
1. Bypass and remove the sectionalizer from service.
2. Inspect external components.
A. Check for broken or cracked bushings, paint scratches,
and other mechanical damage.
B. Note the counter reading and enter the reading in the
record log.
C. Close and trip the sectionalizer manually several times to
check the manual operators. Leave the sectionalizer in the
tripped position.
3. Loosen the bolts that secure the head casting and remove
the mechanism from the tank. (If tank and head do not
separate readily, break the gasket seal by prying them
apart.)
A. Allow oil to drain off mechanism.
4. Inspect contacts for erosion. Refer to Contact Inspection
procedure, within this manual, for inspection instructions.
A. Slight pitting and discoloration can be dressed with crocus
cloth.
B. Replace moving and stationary contacts if they are severe-
ly eroded.
5. Clean all internal components.
A. Remove all carbon traces by wiping with a clean, lint-free
cloth.
B. Flush the internal mechanism with clean, dry transformer
oil.
6. Replace head gasket. Use Pliobond to retain new gasket.
7. Inspect tank liners.
A. Soft or spongy areas indicate that water has been
absorbed. Replace liners if this condition exists.
8. Check the dielectric strength of the insulating oil.
A. The dielectric strength should not be less than 22 kv.
B. Low dielectric strength usualIy indicates the presence of
water. There are gasket seals between each bushing and
the head. Check the seals carefully for deterioration or
entrance of moisture.
NOTE: The unit employs a vented oil-level gage and filler
plug. Make sure vent is free and clear to allow unit to
breathe with changes in atmospheric conditions. Normal
breathing will prevent a seal from breaking which can
instigate a path for moisture to enter the tank.
9. Inspect circuit components attached to the recloser head
and operating mechanism.
A. Check condition of wiring to terminal strips, make sure all
connections are tight.
B. Check condition of bushing current transformers and
associated wiring.
C. Check condition of microswitches and wiring.
10. If oil must be replaced.
A. Drain tank and clean out all sludge and carbon deposits.
B. Fill tank with clean insulating oil to 7/8 in. from top of tank,
with mechanism removed. Capacity is approximately 42
gallons. See Oil Condition following.
11. Replace mechanism into tank.
A. Install head bolts and tighten evenly to 35 55 ft-lbs torque.
12. Manually close and trip the unit several times to check for
proper operation of the mechanism.
13. Perform an insulation withstand test (see page 7 for
procedure).

S270-20-5
7
Figure 9.
Test circuit schematic.
Oil Condition
Oil provides the internal insulation barrier between phases
and from phase to ground, and must be replaced before it
deteriorates below a safe dielectric level. Replace the oil if its
dielectric strength falls below 22 kv.
New oil should always be filtered before use even though it
is obtained from an approved source. Passing the oil through
a blotter press will remove free water and solid contaminants
such as rust, dirt, and lint. Keep aeration to a minimum dur-
ing filtering to prevent moisture in the air from condensing in
the oil and lowering its dielectric strength.
Used oil must be treated before reusing. Filtering may
remove absorbed and free water and other contaminants to
raise the dielectric strength to acceptable levels. However, fil-
tering does not always remove water-absorbing contami-
nants and the dielectric strength may fall rapidly after being
returned to service. Therefore the sectionalizer should be
filled with new oil, or oil that has been restored to like-new
condition. Oil supplied in sectionalizers conforms to ASTM
Standard D3487, Type l; its property limits are shown in
Reference Data R280-90-1, “Oil Specifications and Tests.”
Insulation Level Withstand Tests
High-potential withstand tests provide information on the
dielectric condition of the sectionalizer. Testing is performed
at 75% of the rated low-frequency withstand voltage 52.5 kv
test voltage.
TEST 1: Proceed as follows:
1. Manually close main contacts.
2. Ground sectionalizer tank and head.
3. Connect all three source-side bushings (1, 3, 5) together.
4. Apply proper test voltage to source-side bushings.
5. The sectionalizer should withstand the test voltage for 60
seconds.
TEST 2: Proceed as follows:
1. Manually close main contacts.
2. Ground sectionalizer tank and head.
3. Ground Phase A (bushing 2) and Phase C (bushing 6).
4. Apply proper test voltage to Phase B (bushing 3).
TEST 3. Proceed as follows:
1. Open main contacts of sectionalizer.
2. Ground sectionalizer tank and head.
3. Connect and ground all three load-side bushings (2, 4, 6).
4. Connect all three source-side bushings (1, 3, 5).
5. Apply proper test voltage to source-side bushings.
6. The sectionalizer should withstand the test voltage for 60
seconds.
7. Reverse the connections: ground source-side bushings (1,
3, 5); apply test voltage to load-side bushings (2, 4, 6) for
60 seconds.
8. The sectionalizer should withstand the test voltage for 60
seconds.
TEST RESULTS: These high potential withstand tests pro-
vide information on the dielectric condition of the sectionaliz-
er and the integrity of the contacts.
A. If the sectionalizer passes the closed-contacts tests
(Tests 1 and 2) but fails the open-contacts test (Test 3)
a deterioration of one or more of the contact assem-
blies is likely to be the cause. Check each contact
assembly individually to determine the failed phase or
phases, and replace. Retest to confirm repair.
B. If the sectionalizer fails the closed-contacts tests (Test
1 and 2) the cause is likely to be a diminished electri-
cal clearance, low oil dielectric strength or failed insu-
lation. After correcting the problem, retest to confirm
repair.
TEST PROCEDURES AND
TROUBLESHOOTING
The following test procedures are recommended to check the
operating condition and to determine possible trouble areas in a
malfunctioning unit:
Test Circuit and Equipment
A suggested test circuit is shown in Figure 9. In this test setup
the test current is obtained by back-feeding a 600:5 amp current
transformer (located in the primary loop of one phase of the sec-
tionalizer) from an adjustable 120 vac source. The ammeter
scales should be selected to accommodate the appropriate
range of test currents.
IMPORTANT: Before performing any of the test
procedures that follow, make sure the 120 vac
power to the heater and voltage charging board is dis-
connected to disable the voltage restraint feature. The
sectionalizer will not count as long as the voltage
restraint feature (part of the voltage charging board) is
energized.
!

8
Type GW Maintenance Instructions
Test Procedures
MINIMUM ACTUATING CURRENT
The minimum actuating current can be verified by testing at the
±ten percent values of the phase and ground actuating current
ratings. For example, the minimum actuating resistor rated at
80 amps is tested at 72 amps (no-count) and 88 amps (count
registered).
PHASE MINIMUM ACTUATING CURRENT
When checking the phase minimum actuating current, the
ground fault sensing portion of the sectionalizer must be dis-
abled. Testing an individual phase without disabling the ground
sensing circuits will cause a false count. The following proce-
dure can be used:
1. Jumper the ground actuating current resistor with a short
lead to disable the ground sensing circuit.
2. Program sectionalizer for one count-to-open by setting the
COUNTS TO OPEN SELECTOR switch to “1”.
3. Close sectionalizer by operating the close pullring the
required number of times.
4. With the test circuit connected to phase A of the sectionalizer
and S1 open, hold S2 closed and slowly raise the test cur-
rent from zero to the appropriate value shown in Column A
of Table 1.
5. Release S2 to simulate a backup opening. The sectionalizer
should not open.
6. Close S2 and adjust the test current to the appropriate value
shown in Column B of Table 1.
7. Release S2 to simulate a backup opening. The sectionalizer
should count the overcurrent interruption and open.
8. Repeat steps 3 through 7 for phases B and C.
9. Remove the jumper from across the ground actuating cur-
rent resistor upon completion of this portion of the test.
GROUND MINIMUM ACTUATING CURRENT
To prevent the possibility of a false count, the phase sensing
portion of the sectionalizer control circuit should be disabled
when the ground minimum actuating current is being checked.
The following procedure can be used:
1. Jumper the phase actuating current resistor with a short lead
to disable the phase sensing circuit.
2. Check that sectionalizer control is set for one count-to-open.
3. Close sectionalizer by operating close pullring the require
number of times.
4. With the test circuit connected to phase A of the sectionalizer
and S1 open, hold S2 closed and slowly raise the test cur-
rent from zero to the appropriate value shown in Column A
of Table 1.
5. Release S2 to simulate a backup opening The sectionalizer
should not open.
6. Close S2 and adjust the test current to the appropriate value
shown in Column B of Table 1.
7. Release S2 to simulate a backup opening. The sectionalizer
should count the overcurrent interruption and open.
8. Repeat steps 3 through 7 for B and C phases.
9. Remove the jumper from across the phase actuating current
resistor.
COUNT RESTRAINT
The count restraint feature prevents erroneous counts of over-
currents interrupted by downline protective devices by blocking
the counting operation as long as a minimum of one-half amp
of uninterrupted line current flows through the sectionalizer.
The operation of the count restraint can be verified by super
imposing an interruptable overcurrent on a constant minimum
line current. The sectionalizer will not count or open on the
interruption of the overcurrent as long as the minimum line cur-
rent is not interrupted. To check the ground restraint feature,
proceed as follows:
1. Jumper the ground actuating current resistor with a short
lead to disable the ground sensing circuit.
2. Check that sectionalizer is set for one count-to-open.
3. Close sectionalizer by operating close pullring the required
number of times.
4. With the test circuit connected to phase A of the sectionalizer
and S1 closed (to simulate a constant load current of
approximately six amps), hold S2 closed and raise the test
current to slightly above the appropriate value shown in
Column B of Table 1.
5. Release S2 to simulate a downline device clearing the over-
current. The sectionalizer should not open verifying the oper-
ation of the count restraint feature.
6. Open S1 and again close and release S2 to simulate a back-
up device clearing the fault. This time the sectionalizer
should count the overcurrent interruption and open.
Table 1
Test Circuit Operating Limits for Actuating Current
Settings
Column A Column B
Actuating Sectionalizer Must Sectionalizer Must
Current Setting Not Count Below Count At
(amps) (amps) (amps)
3.5 3 4
7 6.3 7.7
16 14.4 17.6
20 18 22
24 21.6 26.4
28 25.2 30.8
40 36 44
56 50.4 61.6
80 72 88
112 101 124
160 144 176
224 201 247
256 230 282
296 266 326
320 288 352
384 345 422
448 403 493
640 576 704
768 691 845
896 806 986
VOLTAGE RESTRAINT
When energized at 120 vac, the voltage charging board provides fast
charging times for the trip energy storage capacitors. It also acts as a
voltage restraint; the sectionalizer will not count an overcurrent inter-
ruption of the backup protective device unless the voltage at the con-
trol is also interrupted. To check the voltage restraint feature, proceed
as follows:
1. Jumper the ground actuating resistor with a short lead to dis-
able the ground sensing circuit.
2. Program sectionalizer for one count-to-open.
3. Close sectionalizer by operating close pullring the required
number of times.
4. Connect 120 vac across pins B and D of the 120 vac input
receptacle.
5. With the test circuit connected to phase A of the sectionalizer
and S1 open, close S2 and raise the current to slightly
above the appropriate value shown in Column B of Table 1.
6. Release S2 to simulate a downline device clearing the over-
current. The sectionalizer
should not open.
7. Disconnect the 120 vac from the input receptacle.
8. Again close and release S2. The sectionalizer should open.
NUMBER OF COUNTS-TO-OPEN
The number of counts-to-open can be verified by interrupting an
overcurrent through the sectionalizer for a preset number of times.
For example, with the control set for three counts, the sectionalizer
will open upon the third overcurrent interruption. Proceed as follows:

S270-20-5
9
1. Jumper the ground actuating current resistor with a short
lead.
2. Program sectionalizer for three counts-to-open by setting
the COUNTS-TO-OPEN SELECTOR switch to “3”.
3. Close sectionalizer by operating the close pullring the
required number of times.
4. With the test circuit connected to phase A of the section-
alizer and S1 open, close S2 and raise the test current
to slightly above the appropriate value shown in Column
B of Table 1.
5. Open and close S2 a number of times. The sectionalizer
should open upon the third opening of S2.
6. To verify the two-counts-to-open setting, set the
COUNTS-TO-OPEN SELECTOR switch to “2” and
repeat steps 3 through 5. The sectionalizer should open
upon the second opening of S2.
COUNT RESET
The count reset feature resets the sectionalizer count to
zero whenever current below the actuating level flows
through the sectionalizer for longer than the programmed
reset time without interruption. The reset time settings have
a tolerance of ± 10 percent. It can be verified by interrupting
an overcurrent flow through the sectionalizer one time less
than the counts-to-open setting, then allowing load current
to flow for periods just under and just over the reset setting.
The sectionalizer should open if the overcurrent for the final
count is interrupted within the reset time period (reset has
not activated). The sectionalizer should not open if the over
current for the final count is interrupted after the reset time
period (count has reset to zero). The following procedure
may be used to verify the count reset.
1. Jumper the ground actuating current resistor with a
short lead to disable ground sensing circuit.
2. Program sectionalizer control for 2 COUNTS-TO-OPEN
and set the COUNT RESETSELECTOR to 15 seconds.
3. Close sectionalizer by operating close pullring the
required number of times.
4. With test circuit connected to phase A of the sectionaliz-
er and S1 open, close S2 and raise the test current to
slightly above the appropriate value shown in Column
B of Table 1.
5. Release S2 to simulate a backup protective device
clearing the overcurrent. The sectionalizer will register
a count.
6. Close S1 for 13.5 seconds.
7. Momentarily close and then release switch S2. The sec-
tionalizer should open, verifying that the count reset
has not been activated.
8. Reclose sectionalizer and then close and release S2
once to register one overcurrent interruption count.
9. Close S1 for slightly more than 22 seconds.
10. Momentarily close and release switch S2. The section-
alizer should not open verifying that the count reset has
been activated and the first count has been erased.
11. Again close and release S2. The sectionalizer should open.
INRUSH-CURRENT RESTRAINT
The inrush-current restraint feature distinguishes between fault
currents and inrush currents. For fault current interruptions, the
sectionalizer counts and opens normally. For an inrush-current
condition, the phase minimum actuating current is raised by a
preset multiple for a preset time and ground fault detection is
blocked for a preset time to prevent counting the inrush current.
The operation of the inrush-current restraint can be verified by
simulating a fault condition (the overcurrent is preceded by an
overcurrent interruption) and an inrush condition (the overcur-
rent is preceded by a load current interruption). The following
procedure may be used to verify the inrush current restraint
feature.
1. Jumper the ground actuating current resistor with a short
lead to disable the ground sensing circuit.
2. Set the COUNTS-TO-OPEN SELECTOR switch to “1” and the
PHASE ACTUATING LEVEL MULTIPLIER switch to X2.
3. Set the GND INRUSH RESET and the PHASE INRUSH
RESET switches to TEST.
NOTE: In the TEST position, the inrush restraint is blocked from
resetting once it is activated.
4. Close sectionalizer by operating close pullring the required
number of times.
5. With test circuit connected to phase A of the sectionalizer and
S1 open, hold S2 closed and raise the test current to slightly
below the appropriate value shown in Column A of Table 1.
6. Release S2 to simulate a backup opening with only load cur-
rent flowing through the sectionalizer when current was inter-
rupted. The sectionalizer should not open.
7. Close S2 and adjust the test current to just below twice the
appropriate value shown in Column A of Table 1 to simulate
an inrush condition.
8. Release S2. The sectionalizer should not open, verifying that
the inrush restraint feature has been activated.
9. Reset inrush restraint as follows:
A. Return the GND INRUSH RESET and the PHASE INRUSH
RESET switches to some finite values.
B. Hold S2 closed longer than the greater of the two settings
to reset the inrush restraint feature.
C. Return both GND INRUSH RESET and PHASE INRUSH
RESET switches to TEST.
10. Again hold S2 closed and raise the test current to slightly
below the appropriate value shown in Column A of Table 1.
11. Release S2 to simulate a backup opening with only load cur-
rent flowing through the sectionalizer when current was inter-
rupted.
12. Close S2 and adjust the test current to slightly twice the value
shown in Column B of Table 1.
13. Release S2. The sectionalizer should trip verifying the 2X
phase actuating level multiplier setting.
14. Manually close the sectionalizer and repeat step 9 to reset the
inrush restraint feature.
15. Close S2 and raise the test current to slightly above the
appropriate value shown in Column B of Table 1.
16. Release S2 to simulate a backup opening with fault current
flowing through the sectionalizer when current was interrupt-
ed. The sectionalizer should open.
17. Close the sectionalizer.
18. Repeat step 15 to simulate a fault condition.
19. ReleaseS2.The sectionalizer should open verifying that the
inrush restraint feature has not been activated.
Post-Test Procedures
After testing has been completed, make sure the control settings
are programmed to the operating parameters as originally
specified.
TROUBLESHOOTING
Sectionalizer troubleshooting is the process of evaluating prob-
lems that are encountered and determining the cause. The fol-
lowing procedure is recommended.
1. Check for loose or broken connections and wiring. Figure 10
shows the interconnection between the various electrical com-
ponents of the sectionalizer.
2. Check the toggle and associated linkage and springs for
mechanical binding by closing the sectionalizer and tripping it
manually several times.
3. Perform the applicable electrical test described in the Test
Procedures section of these instructions. If the sectionalizer
does not trip under test either the control or the bi-stable actua-
tor assembly may be malfunctioning.

10
Type GW Maintenance Instructions
GVA202C (R5)
Figure 10.
Type GW sectionalizer interconnection diagram.

S270-20-5
11
Figure 12.
Removing bushing.
Figure 11.
Manual and electrical trip linkage.
A. Check the bi-stable actuator assembly to see if it has—or
has not—released.
NOTE: There should be approximately 1/32-in. play between the
end of the trip rod and the lever assembly on the main shaft
(Figure 13).
(1 ) If the bi-stable actuator assembly actuated the toggle
assembly should be released. If the malfunction is the
result of mechanical binding of the toggle orthe associ-
ated linkages check the engagement surface of the
toggle to make sure there are no rough spots or burrs.
Repair as required.
(2) If the bi-stable actuator assembly did not actuate,
check the d-c resistance of the trip coil:
With the red and the brown leads removed from the
control circuit board the resistance should measure
approximately 6.5 ohms.
If the bi-stable actuator assembly is damaged or
inoperative it must be replaced. Make sure there is
approximately 1/32-in. play between the end of the trip
rod and the lever assembly on the main shaft (Figure
11) when the new bi-stable actuator is installed.
(3) If the bi-stable actuator assembly appears to be opera-
tive, check the Zener diode, mounted above the volt-
age charging circuit board. If the Zener diode is dam-
aged replace it.
NOTE: The dc voltage across the zener diode will be approxi-
mately 18 Vdc, with any load current over 10 amps flowing
through the sectionalizer.
B. If all components check out satisfactorily, the problem is in
the control printed circuit board assembly, replace the
board and retest.
Bushings
Bushing maintenance generalIy consists of a thorough clean-
ing and a careful examination for chips, cracks or other
mechanical damage during the periodic maintenance inspec-
tion. Bushings must be replaced whenever damage is discov-
ered. Refer to Figure 12 and proceed as follows:
1. Remove head-clamp bolts and untank sectionalizer.
2. Remove nut, lockwasher, and flatwasher holding the lower
end of bushing rod to contact housing bracket.
3. Remove the three hex head capscrews and clamps that
secure the bushing to the head and lift out.
4. Remove and discard the lower bushing gasket.
5. Twist off the split aluminum clamping ring from the old
bushing and install on the new bushing, if it is in good con-
dition—replace if damaged.
NOTE: The clamping ring cushions and distributes the pressure
between the ceramic and the clamps. DO NOT OMlT.
6. Install new bushing into head, use a new lower bushing
gasket.
7. Position bushing with the stud end of the terminal pointing
outward.
8. Position the clamping ring with the split centered between
two clamping bolts.
9. Reassemble bushing to head casting. Tighten bolts even-
ly, a little at a time, to a torque of 10-15 ft-lbs.
NOTE: Clamping forces must be applied gradually and equally in
rotation to each bolt. This results in an evenly distributed gasket
sealing pressure.
10. Reconnect lead to contact housing bracket.
SHOP MAINTENANCE PROCEDURES
The operations described in this section should be performed
under the cleanest conditions possible. The repair work,
except for bushing replacement, will be simplified if the work
bench is arranged so the mechanism/head assembly can be
inverted (bushings down). No special tools are required for
any of the repair procedures.

12
Type GW Maintenance Instructions
Figure 13.
Contact arrangement.
Figure 14.
Movable contact.
Figure 15.
Moving contact clearance.
88919KMA
88918KMA
Contacts
Open sectionalizer contacts and remove head mechanism
from tank. Operate sectionalizer manually several times, while
observing the contacts, to make sure contacts mate properly;
leave in open position.
The contacts used in the Type GW sectionalizer are self-
cleaning through the wiping action of the contacts. When ero-
sion has spread to the load-current transfer surfaces of the
moving contacts the entire contact assembly must be
replaced. Use the following procedure for contact inspection
and replacement, as required.
CONTACT INSPECTION
The movable contact yoke assembly must be removed for
contact inspection, refer to Figure 13.
1. Remove stop nut and washer.
2. Carefully drive out roll pin.
3. Note arrangement of flat washers above and below the
movable contact yoke, they must be replaced in the exact
same order.
4. Remove contact yoke assembly and inspect (Figure 14).
• Arcing tips of the moving contacts can experience consid-
erable erosion before replacement is necessary. Slight
pitting and discoloration can be dressed with crocus
cloth.
• If one-half or more of the contact load surface is worn
away the complete contact assembly (movable and sta-
tionary contacts) must be replaced. Refer to Stationary
Contact Assembly section of these instructions for sta-
tionary contact replacement instructions.
5. Install washers, as removed, and movable contact yoke
assembly.
6. Install elastic stop nut and carefully tighten, do not over
tighten.
STATIONARY CONTACT ASSEMBLY
To replace the stationary contact assembly:
1. Remove movable contact yoke assembly, refer to Contact
Inspection section of these instructions for removal proce-
dure.
2. Remove the lower bushing nuts securing stationary contact
assembly to bushing assemblies (Figure 13).
3. Lift contact assembly off bushings.
4. Operate actuator mechanism until it is in the switch-closed
position.
5. Place the new stationary contact assembly on the upper
bushing washers. Loosely install lower flat washer, lockwash-
er and lower bushing nuts.
6. Install the new movable contact yoke assembly, refer to
Contact Inspection section for installation procedure.
7. Adjust upper bushing nuts to provide 1/32” (.8 mm) clearance
between moving contact assembly and contact tubes, refer
to Figure 15.

Figure 16.
Squaring contact housing.
S270-20-5
13
88921KMA
889228MA
88920KMA
Figure 17.
Contact rod linkage.
Figure 18.
Setting stop bolt.
8. Square contact housing with head casting bottom as
shown in Figure 16.
9. Recheck moving contact assembly for proper clearance
(refer to Figure 15).
10. Tighten lower bushing nuts to secure stationary contact
assembly.
11. Refer to Contact Alignment section of these instructions
for proper adjustment of contacts.
CONTACT ROD
To replace the contact rod:
1. With the switch mechanism removed from the tank,
remove moving contact assembly, refer to Contact
Inspection section for removal instructions.
2. Remove lower bushing nuts, lockwasher and flat washer
securing stationary contact assembly, Figure 13.
3. Lift contact assembly off bushings.
4. Remove C-ring and pin securing contact rod to shaft lever
(Figure 17).
5. Attach new contact rod to shaft lever with pin and C-ring
removed (Figure 17).
6. Place contact assembly over contact rod and onto upper
bushing washers. Loosely install lower flat washer, lock-
washer and jam nut.
7. Install movable contact yoke assembly, refer to Contact
Inspection section for installation instructions.
8. Adjust upper bushing nuts to provide 1/32” (.8 mm) clear-
ance between moving contact assembly and contact
tubes, refer to Figure 15.
9. Square contact housing with head casting bottom as
shown in Figure 16.
10. Recheck contact assembly for proper clearance (refer to
Figure 15).
11. Tighten lower bushing nuts to secure stationary contact
assembly.
12. Refer to Contact Alignment section of these instructions
for proper adjustment of contacts.
CONTACT ALIGNMENT
1. Make sure the clearance between the moving contact
assembly and the stationary contact tubes is 1/32 in. with
the contacts full closed (Figure 15).
A. To obtain the 1/32 in. clearance, adjust the stationary
contact assembly at the upper bushing nuts.
2. With the contacts fully open, check to make sure that the
contact rod piston does not bottom in the stationary contact
assembly dashpot.
A. To prevent bottoming, set the stop bolt, inside the operat-
ing housing, (Figure 18) so that the slotted side plates of

Type GW Maintenance Instructions
14
Figure 19.
Proper stop bolt adjustment.
Figure 21.
Test circuit for checking bushing current transformers.
Figure 20.
CT protection board.
the latch assembly at the upper pivot bear snugly
against the pivot pin when the latch is in the toggle posi-
tion as shown in Figure 19.
(1) Check this by manually winding the actuator mech-
anism.
a. The pivot pin should touch the end of the slot just
as the latch assembly reaches the toggle posi-
tion.
3. Retank the sectionalizer.
Current Transformers
Type GW sectionalizers are equipped with six 1000:1 current
sensing transformers. Two are installed over the shank of each
source side bushing, underneath the head casting. The leads
from the current transformers are routed to a through connector
and then into the mechanism housing to the CT protection board,
see Figure 20. To test the current transformers proceed as fol-
lows:
87910KMA
CONTINUITY CHECK
1. Disconnect white CT lead from phase A connector on CT pro-
tection board. Measure resistance between white lead and
phase A, B, and C leads (connected to CT protection board).
Approximately 11.4 ohms should be measured. Replace
white lead.
2. Disconnect yellow and red CT leads, from ground connectors
on CT protection board. Measure resistance between leads.
Approximately 3.8 ohms should be measured. Replace leads.
RATIO TEST FOR SENSING CT’s
1. Connect all three phases of the sectionalizer in series, as
shown in Figure 21, and close sectionalizer.
2. Connect a 100 ampere ac test circuit to test points 1 and 2, do
not energize.
3. Remove the black CT lead from phase A on the CT protection
board. Insert a 0-500 milliammeter between black lead and
white CT lead.
4. Energize 100 ampere source and observe the millammeter.
The meter should record 100 ma ±10%. Deenergize source
and reconnect lead.
NOTE: Be sure to allow for the tolerances of meter being used. The
resistance of certain type of meters is not negligible. Use as high a
scale (lower resistance) as is accurately readable.
5. Repeat test on phases B and C.
6. Remove red and yellow ground CT leads from CT protection
board. Insert a 0-500 millammeter between red and yellow
leads.
7. Energize 100 ampere source and observe millammeter. The
meter should record 300 ma ±10%. Deenergize source and
reconnect leads.
POLARITY TEST FOR SENSING CT's
1. With phases still connected in series, from previous test,
remove three black leads from phase connectors on CT pro-
tection board. Temporarily connect black leads together.
Insert a 0-500 millammeter between black leads and white
phase CT lead.
2. Energize 100 ampere source and observe millammeter. The
meter should record 300 ma ±10%. Deenergize 100 ampere
source and reconnect leads.
A. All three transformers should have the same polarity; the
output should measure 300 ma.
B. If one transformer has its polarity opposite of the remaining
two the output will measure 100 ma.

S270-20-5
15
CT Protection Board
The CT protection board provides automatic protection for the
bushing mounted CTs. The protection board is located on the
right side of the mechanism frame, within the mechanism
housing. The following test can be used to determine if the
protection board is working properly.
Assemble and connect the equipment as shown in Figure
22, which shows the test voltage being applied to phase A.
1. Unplug wire harness from control printed circuit board
assembly.
2. Slowly increase the voltage on the variable transformer
while observing the voltage between the 1000:1 CT leads.
3. At approximately 115 volts, the voltage should drop off even
though the voltage from the variable transformer is
increased.
If the voltage does not drop off, the CT protection board is
damaged and must be replaced.
4. Disconnect input power and reconnect to test phase B, phase
C and ground.
5. Reconnect wire harness onto control printed circuit board
assembly.
SERVICE PARTS LIST
When ordering service parts, always include the sectionalizer
type and serial number. Because of McGraw-Edison’s continu-
ous-improvement policy, there will be cases in which parts
ordered may not be the same as the parts furnished; however,
they will be interchangeable. All parts have the same warranty as
any whole item of switchgear; i.e., against defects in material or
workmanship within one year from the date of shipment.
Figure 22.
Testing CT protection circuit.

Type GW Maintenance Instructions
16
Figure 23.
Bushing parts and contact assembly.

Bushings and Contacts (Figure 23)
S270-20-5
17
Qty.
Item Catabg per
No. Description Number Assy.
7 Gasket KP11 93RA 6
8 Clamping ring KP1111R 6
9 Bushing clamp KP1109R900 18
10 Capscrew, hex hd, 3/8-16 x
2-1/4, stl K730101137225Q 18
11 Bushing assembly
Standard bushing KA56RV1 6
Standard bushing with BCT KA56RV2 6
Qty
Item Catalog per
No. Description Number Assy.
1 Contact rod assembly
(includes item 3) KA104GW 3
2 Stationary contact assembly KA107GW 3
3 Movable contact assembly KA102GW1 3
4 Jam nut, hex, 1/2-20, brass K880625120050H 12
5 Split lockwasher, 1/2, med
bronze K900830050000A 6
6 Washer, 9/16, brass K900225056125H 12

Type GW Maintenance Instructions
18
Figure 24.
Head and tank assemblies.

Qty
Item Catalog per
No. Description Number Assy.
1 Head assembly KP504GW2 1
2 O-ring KP2000A9 1
3 Plug and gauge assembly KA118GW 1
4 Lifting lug KP456H2 2
5 Lockwasher, med, 5/8, stl K900801062000Z 2
6 Capscrew, hex head, 5/8-11 x
1-1/2, stl K730101162150Q 2
7 Washer KP2028A23 10
8 Capscrew, hex head, 1/2-13 x
3-1 /4, stl K732401150325Q 10
9 Gasket KP2103A8 1
10 Support KP145RE 9
11 Current transformer assembly KA43GV 6
12 Spacer KP3009A88 12
13 Washer, #14, brass K900525026056A 6
14 Lockwasher, 1/4, med, stl K900801025000Z 10
15 Capscrew, hex head, 1/4 20 x 4,
stl K730101125400Y 6
16 Gasket KP611R 1
17 Cover plate KP609R 1
18 Capscrew, hex head, 1/4-20 x
5/8, stl K730101125062Z 4
19 Spacer KP3017A18 6
20 Bearing plate KP502GW 1
21 Lockwasher, 1/2, med, stl K900801050000Z 6
22 Capscrew, socket head, 1/2-13
x 1-1/2, stl KP2036A11 6
23 Bearing KP88VR 3
24 Lockwasher, 5/16, med, stl K900801031000Z 6
Head and Tank Assemblies (Figure 24)
S270-20-5
19
Qty
Item Catalog per
No. Description Number Assy.
25 Capscrew, hex head, 5/16-13 x
2, stl K730101131200Y 6
26 Tank liner KP52SGW 2
27 Tank liner KP524GW 1
28 Tank liner support KP22SW 2
29 Tank assembly KA18GW 1
30 Pipe nipple KP2039A1 1
31 Valve KP2038A1 1
32 Pipe plug KP2007A3 1
33 Position indicator assembly KA19VR 1
34 Roll pin, 3/16 x 1-1/8 K970801188113Z 1
35 Bushing KP3106A9 1
36 Lever and shaft assembly
(includes items 32 and 33) KA103GW 1
37 Retaining ring, WA514, 1/4, stl K97091250000A 12
38 Link KP510GW 6
39 Pin KP3124A69 6
40 Machine screw, rd hd, #8-32 x
3/8, stl K721501108037Z 3
41 Lockwasher, #8, med, stl K900801008000Z 3
42 Cable clamp KP2006A1 2
Cable clamp KP2006A8 1
43 Wire retainer K994904170003A 3
44 Connector assembly KA201GV 1
45 O-ring KP2000A6 1
46 Spirap, 1-1/2” KP2072A1 1
47 Ground connector KP392RA 1
48 Collar KP138VLM 1
49 Screw, hex set, 1 /4-20 x 3/8 K762315125037A 1

Type GW Maintenance Instructions
20
Figure 25a.
Operating mechanism.