Powell Power/Vac ML-17 User manual

01.4IB.50100 Power/Vac®
ML-17 Mechanism
For use with all Power/Vac® Electrical
Ground and Test Devices
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Contact Information
Powell Electrical Systems, Inc.
www.powellind.com
[e-mail]
Service Division
PO Box 12818
Houston, Texas 77217-2818
Tel: [phone]
Fax: [phone]
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Power/Vac® Electrical Ground and Test Devices
Equipped with ML-17 Mechansim
01.4IB.50100

Signal Words
As stated in ANSI Z535.4-2007, the signal word is
a word that calls attention to the safety sign and
designates a degree or level of hazard seriousness.
The signal words for product safety signs are
“Danger”, “Warning”, “Caution” and “Notice”.
These words are defined as:
DANGER indicates an imminently hazardous
situation which, if not avoided, will result in
death or serious injury.
!
DANGER
!
WARNING
WARNING indicates a potentially hazardous
situation which, if not avoided, could result in
death or serious injury.
!
CAUTION
CAUTION, used with the safety alert symbol,
indicates a hazardous situation which, if not
avoided, could result in minor or moderate
injury.
CAUTION, used without the safety alert
symbol, is used to address practices not
related to personal injury.
CAUTION
NOTICE
NOTICE is used to address practices not related
to personal injury.
Qualified Person
For the purposes of this manual, a qualified
person, as stated in NFPA 70E®, is one who has
skills and knowledge related to the construction
and operation of the electrical equipment and
installations and has received safety training to
recognize and avoid the hazards involved. In
addition to the above qualifications, one must also
be:
1. trained and authorized to energize,
deenergize, clear, ground, and tag circuits
and equipment in accordance with
established safety practices.
2. trained in the proper care and use of
personal protective equipment (PPE)
such as rubber gloves, hard hat, safety
glasses or face shields, flash clothing, etc.,
in accordance with established safety
practices.
3. trained in rendering first aid if necessary.
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01.4IB.50100

Contents
Ch 1 General Information ................................................................................................1
A. Scope ...............................................................................................................................................................2
B. purpoSe ............................................................................................................................................................2
c. InStructIon BulletInS AvAIlABle electronIcAlly ....................................................................................................3
Ch 2 Safety .......................................................................................................................4
A. SAfe Work condItIon .........................................................................................................................................4
B. SAfety GuIdelIneS ...............................................................................................................................................4
c. GenerAl ............................................................................................................................................................5
d. SpecIfIc .............................................................................................................................................................5
e. SAfety lABelS ....................................................................................................................................................5
Ch 3 Equipment Description ............................................................................................6
A. GenerAl ............................................................................................................................................................6
B. Ml-17H GenerAl deScrIptIon (63kA only) ........................................................................................................6
c. operAtIon .........................................................................................................................................................7
1) Close Spring Charging ............................................................................................................................................................ 7
2) Closing Operation ................................................................................................................................................................... 8
3) Opening Operation ................................................................................................................................................................. 8
4) Trip Free Operation ...............................................................................................................................................................12
d. InterlockS ...................................................................................................................................................... 12
1) Closing Spring Discharge Interlock ...................................................................................................................................12
2) Negative Trip Interlock .........................................................................................................................................................12
3) Positive Interlock ....................................................................................................................................................................12
4) Closing Spring Gag Interlock ..............................................................................................................................................12
Ch 4 Installation .............................................................................................................13
A. receIvInG ........................................................................................................................................................ 13
B. HAndlInG ....................................................................................................................................................... 13
c. StorAGe ......................................................................................................................................................... 13
d. SHIppInG poSItIon ............................................................................................................................................ 14
Ch 5 Mechanical Checks and Adjustments ....................................................................15
A. GenerAl ......................................................................................................................................................... 15
B. SloW cloSInG operAtIon ................................................................................................................................. 15
c. pull rod AdjuStMent ..................................................................................................................................... 17
d. trIp lAtcH cleArAnce ...................................................................................................................................... 17
e. overtrAvel AdjuStInG BoltS ............................................................................................................................ 18
f. WIpe And GAp AdjuStMent ............................................................................................................................... 18
1) General .....................................................................................................................................................................................18
2) Checking ..................................................................................................................................................................................19
3) Adjustment .............................................................................................................................................................................20
G. prIMAry contAct eroSIon IndIcAtIon ................................................................................................................ 21
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01.4IB.50100

Contents
Ch 6 Electrical Checks ....................................................................................................22
A. HIGH potentIAl teSt ........................................................................................................................................ 22
1) Primary Circuit .......................................................................................................................................................................22
2) Secondary Circuit ..................................................................................................................................................................22
3) Primary Circuit Resistance ...................................................................................................................................................22
4) Vacuum Interrupter Integrity Test .....................................................................................................................................23
Ch 7 Maintenance ..........................................................................................................25
A. recoMMended MAIntenAnce ............................................................................................................................. 25
B. luBrIcAtIon .................................................................................................................................................... 25
Ch 8 Recommended Renewal Parts and Replacement Procedures ..............................26
A. orderInG InStructIonS ..................................................................................................................................... 26
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Power/Vac® Electrical Ground and Test Devices
Equipped with ML-17 Mechansim
01.4IB.50100

Figures
Tables
Figure 1 Typical Schematic for ML-17 Mechanism, Models -4 ....................................9
Figure 2 Typical Schematic for ML-17 Mechanism, Models -4 (continued) ...............10
Figure 3 Toggle Linkage Positions of ML-17 Mechanism View from Rear ................11
Figure 4 Lifting Holes for Overhead Crane ................................................................13
Figure 5 Closing Spring Gag Lock ..............................................................................16
Figure 6 Slow Close Pin on Flywheel ..........................................................................16
Figure 7 Primary Contact Gap and Erosion Indication .............................................18
Figure 8 Wipe Gauge ..................................................................................................19
Table A Wipe and Gap Measurements .............................................................................19
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01.4IB.50100

Ch 1 General Information
The equipment described in this document may contain high voltages and currents which can
cause serious injury or death.
The equipment is designed for use, installation, and maintenance by qualified users of such
equipment having experience and training in the field of high voltage electricity. This document
and all other documentation shall be fully read, understood, and all warnings and cautions
shall be abided by. If there are any discrepancies or questions, the user shall contact Powell
immediately at 1.800.480.7273.
!
WARNING
Before any adjustment, servicing, part replacement, or any other act is performed requiring
physical contact with the electrical working components or wiring of this equipment, the power
supply must be disconnected. Failure to follow this warning may result in injury or death.
!
WARNING
The information in this instruction bulletin is not intended to explain all details or variations of the
Powell equipment, nor to provide for every possible contingency or hazard to be met in connection
with installation, testing, operation, and maintenance of the equipment. For additional
information and instructions for particular problems, which are not presented sufficiently for the
user’s purposes, contact Powell at 1.800.480.7273.
NOTICE
Powell reserves the right to discontinue and to change specifications at any time without incurring
any obligation to incorporate new features in products previously sold.
NOTICE
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General Information
01.4IB.50100

A. Scope
The information in this instruction bulletin
describes the following Power/Vac®Electrical
Ground and Test Devices:
• 50kA and below, using the 49A or 69A
vacuum bottle, equipped with Revision 1
ML-17 operating mechanism
• 63kA using the 68A vacuum bottle,
equipped with Revision 1 ML-17 operating
mechanism
The “Revision 1” mechanism can be identified
by the “1” in the 8th position of the catalog
number as shown on the nameplate,
i.e., GEPVEGT1xxxxxxxxx.
ML-17/49A and ML-17/69A devices include:
• GMV 1050
• GMV 1051
• GMV 1052
• GMV 1053
• GMV 1054
• GMV 1055
• GMV 1060
• GMV 1061
ML-17H/68A devices include:
• EGT-63-A
• EGT-63-B
B. purpoSe
The information in this instruction bulletin is
intended to provide information required to
properly operate and maintain the
ground and test device described in
Ch 1 General Information, A. Scope.
This instruction bulletin provides:
1. Safety guidelines
2. General descriptions of the operation and
maintenance of the ground and test device
3. Instructions for installation and placing the
ground and test device into service
4. Instructions for part replacement
5. Information for ordering renewal parts
6. Procedure for critical adjustments
7. Illustrations, photographs, and description
of the ground and test device
The illustrations contained in this document
may not represent the exact construction
details of each particular type of ground and
test device. The illustrations in this document
are provided as general information to aid in
showing component locations only.
All illustrations and photos are shown using
deenergized equipment.
Be sure to follow the appropriate safety
precaution while handling any of the
equipment. Failure to do so may result in
serious injury or death.
!
WARNING
To the extent required, the products described
herein meet the applicable ANSI, IEEE, and
NEMA Standards; however, no such assurance
is given with respect to local codes and
ordinances which may vary greatly.
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2General Information
Power/Vac® Electrical Ground and Test Devices
Equipped with ML-17 Mechansim
01.4IB.50100

c. InStructIon BulletInS AvAIlABle electronIcAlly
Changes to the instruction bulletin may be
implemented at any time and without notice.
Go to www.powellind.com to ensure use of
the current instruction bulletin for the Powell
equipment.
NOTICE
For more information visit
www.powellind.com. To contact the Powell
Service Division call 1.800.480.7273 or
713.944.6900, or email
[e-mail].
For specific questions or comments pertaining
to this instruction bulletin email
[e-mail] with the IB
number in the subject line.
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General Information
01.4IB.50100

Ch 2 Safety
A. SAfe Work condItIon
The information in Section A is quoted from
NFPA 70E 2012 - Article 120, 120.1 Establishing an
Electrically Safe Work Condition.
120.1 Process of Achieving an Electrically Safe
Work Condition
1. Determine all possible sources of electrical
supply to the specific equipment. Check
applicable up-to-date drawings, diagrams,
and identification tags.
2. After properly interrupting the load current,
OPEN the disconnecting device(s) for each
source.
3. Wherever possible, visually verify that all
blades of the disconnecting devices are
fully OPEN or that drawout type circuit
breakers are withdrawn to the fully
disconnected position.
4. Apply lockout/tagout devices in accordance
with a documented and established policy.
5. Use an adequately rated voltage detector
to test each phase conductor or circuit part
to verify they are deenergized. Test each
phase conductor or circuit part both
phase-to-phase, and phase-to-ground.
Before and after each test, determine
that the voltage detector is operating
satisfactorily.
Informational Note: See ANSI/ISA-61010-1
(82.02.01)/UL 61010-1, Safety Requirements
for Electrical Equipment for Measurement,
Control, and Laboratory Use - Part 1: General
Requirements, for rating and design
requirements for voltage measurement
and test instruments intended for use on
electrical systems 1000 V and below.
6. Where the possibility of induced voltages
or stored electrical energy exists, ground
the phase conductors or circuit parts
before touching them. Where it could be
reasonably anticipated that the conductors
or circuit parts being deenergized
could contact other exposed energized
conductors or circuit parts, apply ground
connecting devices rated for the available
fault duty.
B. SAfety GuIdelIneS
Study this instruction bulletin and all other
associated documentation before uncrating
the ground and test device.
Each user has the responsibility to instruct
and supervise all personnel associated with
usage, installation, operation, and maintenance
of this equipment on all safety procedures.
Furthermore, each user has the responsibility of
establishing a safety program for each type of
equipment encountered.
It is mandatory that the following rules be
observed to ensure the safety of personnel
associated with usage, installation, operation,
and maintenance of these ground and test
devices.
The safety rules in this instruction bulletin are
not intended to be a complete safety program.
The rules are intended to cover only some of the
important aspects of personnel safety related to
Power/Vac®Electrical Ground and Test Device.
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4Safety
Power/Vac® Electrical Ground and Test Devices
Equipped with ML-17 Mechansim
01.4IB.50100

c. GenerAl
1. Only supervised and qualified personnel
trained in the usage, installation, operation,
and maintenance of the ground and test
device shall be allowed to work on this
equipment. It is mandatory that this
instruction bulletin, any supplements, and
service advisories be studied, understood,
and followed.
2. Maintenance programs must be consistent
with both customer experience and
manufacturer’s recommendations,
including service advisories and instruction
bulletin(s). A well planned and executed
routine maintenance program is essential
for ground and test device’s reliability and
safety.
3. Service conditions and applications shall
also be considered in the development of
safety programs. Variables include ambient
temperature; humidity; and any adverse
local conditions including excessive dust,
ash, corrosive atmosphere, vermin and
insect infestations.
d. SpecIfIc
When operating the ground and test device
safety precautions must be observed.
Improper use can result in death, serious
personal injury, or damage to the
equipment. It is important for the user to
develop specific and safe operating procedures
to be observed when using the ground and
test device.
The following specific safety precautions must
be observed:
1. Do not attempt to ground an energized
circuit. The circuit to be grounded should
always be treated as energized until proven
otherwise.
2. Do not attempt to service the device while it
is installed in a switchgear compartment or
on a lift truck. For service, the device must
be located either on the floor or on a sturdy,
level work bench, and blocked from rolling.
3. Store the electrically operated ground and
test device in a clean, dry area free from
dust, dirt, moisture, caustic atmosphere, and
vermin.
4. Keep all insulating surfaces, which include
primary support insulation and insulation
barriers, clean and dry.
5. Check all primary circuit connections to
make certain that they are clean and tight.
6. Take extreme care while using this device to
avoid contacting “live” or “hot” (energized)
terminals.
e. SAfety lABelS
The equipment described in this document
has DANGER, WARNING, CAUTION, and
instruction labels attached to various locations.
All equipment DANGER, WARNING, CAUTION,
and instruction labels shall be observed
when the ground and test device is handled,
operated, or maintained.
Warning and Caution labels are located in
various places in and on the switchgear and
on the circuit breaker removable element.
Always observe these warnings and caution
labels. Do NOT remove or deface any of these
warning/caution labels.
NOTICE
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Safety
01.4IB.50100

Ch 3 Equipment Description
A. GenerAl
The Power/Vac®Electrical Ground and Test
Device uses sealed vacuum ground switches
to make or break contact between the primary
stud and the equipment ground. Primary
connections to the associated metal-clad
switchgear are made by horizontal bars
and disconnect fingers, electrically and
mechanically connected to the vacuum
interrupters. Molded interrupter supports,
one per phase on a three phase ground and
test device, provide mountings for the primary
bars, interrupters, current transfer fingers,
and heat dissipation fins (where used). The
operating mechanism provides vertical motion
at each phase location in order to move the
lower contact of the vacuum interrupters from
an open position to a spring loaded closed
position and then back to the open position on
command.
The ML-17 mechanism is of the stored energy
type and uses a gear motor to charge a closing
spring. During a closing operation, the energy
stored in the closing spring is used to close the
vacuum interrupter contacts, compress the
wipe springs which load the contacts, charge
the opening springs, and overcome bearing
and other friction forces. The energy then
stored in the wipe springs and opening springs
will open the contacts during an opening
operation.
Closing and opening operations are controlled
electrically by a remote control cable attached
to the front of the ground and test device. For
maintenance and checkout, the closing spring
may be manually charged, and a method for
slow-closing the ground switch is available.
B. Ml-17H GenerAl deScrIptIon (63kA only)
The ML-17H mechanism is a very high energy
unit used in 63kA applications. It has much
stiffer wipe springs to achieve the required
high closing and latching forces. It also has
a double close spring to overcome the forces
of the opening and wipe springs. Special
runbacks and primary fingers are incorporated
to withstand higher peak currents. The use of
#271 Loctite®and jam nuts on many bolts and
hardware make a more durable mechanism.
Also, note that wipe and gap measurements
are different for ML-17H ground and test
devices than for standard ML-17 ground and
test devices. Refer to Table A Wipe and Gap
Measurements for wipe and gap parameters.
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6Equipment Description
Power/Vac® Electrical Ground and Test Devices
Equipped with ML-17 Mechansim
01.4IB.50100

c. operAtIon
1) Close Spring Charging
Figures 1 & 2 show the mechanism
expanded schematically with the primary
contacts open and the closing spring
nearly charged. When the closing spring is
discharged, the flywheel eccentric
(Figure 2, AA) will be about 180 degrees
from where it is shown with respect to
center pivot (Figure 2, CC). The transfer
crank (Figure 1, #14) will be rotated
counterclockwise, the slotted link
(Figure 1, #17) will be holding the close
toggle (Figure 1, #20 & Figure 2, #21)
against the frame through link
(Figure 1, #19), and the trip latch
(Figure 1, #18) will be held out of
engagement clockwise by the trip
toggle roller (Figure 2, #52). The
toggle linkage will appear as shown in
Figure 3 (d). When the closing spring
is discharged, switch operator
(Figure 2, #44), operates the motor limit
switch (Figure 2, #43). If the close latch
checking switch (Figure 1, #5) is made and
power is available, the gear motor
(Figure 2, #45) will drive the wind hub
(Figure 1, #11) counterclockwise. Slow
close pawl (Figure 1, #10) will be held out
of possible engagement with the wind hub
notch by the action of the slow close pin
(Figure 2, #48).
After some rotation of the wind hub at
no load, its notch engages the wind pawl
(Figure 1, #9) and rotates the flywheel
counterclockwise, compressing the close
spring assembly (Figure 1, #6) and
rotating the transfer crank (Figure 2, BB)
shaft clockwise by pushing on rod
(Figure 1, #13). As the line of action of
the close spring shifts over center on the
flywheel and attempts to discharge, the
close roller (Figure 1, #3) is blocked by the
close latch (Figure 1, #4) and held until a
closing operation is required. Additionally,
as the close spring goes over center, the
switch operator (Figure 2, #44) is spring
biased into a notch on the front flywheel
(Figure 1, #2). The spring charge indicator
arm (Figure 2, #40) moves clockwise which,
through the action of the rod
(Figure 2, #41) causes a flag (Figure 2, #42)
to indicate“CHARGED”. A cam
(Figure 1, #12) engages the wind pawl
(Figure 1, #9) moving it from contact with
the hub (Figure 1, #11) notch, thereby
allowing the gear motor to coast to a stop
when power is removed by the limit switch
(Figure 2, #43).
As the close spring is compressed, the
slotted link (Figure 1, #17) rises, and the
close toggle (Figure 1, #20 & Figure 2, #21)
forms a more acute angle until the closing
spring goes over center and the trip latch
(Figure 1, #18) is spring biased into place
under the trip roller. When the trip latch is
in place, the latch checking switch
(Figure 2, #47) closes.
With the close spring charged and the
ground and test device open, the toggle
linkage is as shown in Figure 3 (a) .
If control power is lost, or manual operation
desired, the close spring may be manually
charged by using a /”hex socket ratchet
type wrench to rotate the manual charging
wind shaft in the direction indicated by
the arrow until the yellow indicator shows
“CHARGED”.
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Equipment Description
01.4IB.50100

2) Closing Operation
By either energizing the close solenoid
or depressing the manual close button,
the close latch (Figure 1, #4) is rotated
counterclockwise and releases the
close roller (Figure 1, #3) permitting the
flywheel (Figure 1, #1 & #2) to rotate
counterclockwise by the force of the close
spring. This action, transmitted to the
slotted link (Figure 1, #17) by means of
the pull rod (Figure 1, #13) transfer crank
(Figure 1, #14 & #16), pulls the close toggle
through the center against link
(Figure 1, #19) which is tied to the frame.
This action rotates the output crank
(Figure 2, #22) counterclockwise. The
Pole 1 bellcranks (Figure 2, #23), on the
same shaft as the output crank, also rotate
counterclockwise, and by means of the
horizontal connecting bar (Figure 2, #28)
rotate Pole 2 and 3 bellcranks. This rotation
compresses the opening spring
(Figure 2, #29), closes the vacuum
interrupters connected with each operating
rod (Figure 2, #25), and compresses the
wipe spring (Figure 2, #26) on each pole
when the trunnion (Figure 2, #24) continues
moving after the operating rod
(Figure 2, #25) stops. Rotation of an arm
(Figure 2, #34) coupled to the output shaft
(Figure 2, DD) changes the auxiliary switch
(Figure 2, #37) position, and the position
flag (Figure 2, #38) indicates“CLOSED”. The
lever (Figure 2, #44) is moved out of the
notch in the flywheel (Figure 1, #2) and with
the close latch (Figure 1, #4) in position to
catch the close roller, the limit switch
(Figure 2, #43) energizes the gear motor
as described under Ch 3 Equipment
Description, c. operAtIon, 1) Close Spring
Charging. With the ground and test device
closed, closing spring discharged, the
toggle linkage appears as shown in
Figure 3 (b). With the ground and test
device in the closed position, the links
(Figure 1, #17) can move up past the close
toggle without disturbing it as they are
slotted to accommodate a close spring
charged, ground and test device closed, the
toggle linkage appears as shown in
Figure 3 (c).
3) Opening Operation
By either energizing the trip solenoid or
depressing the manual trip button, the trip
latch (Figure 1, #18) is rotated clockwise
permitting the trip toggle (Figure 1, #19 &
#20) to collapse and the vacuum interrupter
contacts to open under the force of the
wipe springs (Figure 2, #26) and opening
spring (Figure 2, #29). At the end of the
opening stroke, a stop block (Figure 2, #30)
on the bottom of the trunnion
(Figure 2, #24) strikes set screws in the
horizontal connecting bar (Figure 2, #28)
which limits the over travel. At the same
time an opening stop is provided by a plate
and buffer assembly (Figure 2, #50). An
opening dashpot (Figure 2, #31) controls
opening velocity and prevents excessive
rebound of the interrupter contacts.
Rotation of the output shaft (Figure 2, DD)
from a closed to an open position operates
the auxiliary switch (Figure 2, #37) as
described in Ch 3 Equipment Description,
c. operAtIon, 2) Closing Operation and
interrupts the trip coil circuit. If the closing
spring is charged, the close toggle can raise
to the top of the slotted link (Figure 1, #17)
thereby permitting the trip toggle to reset
and the trip latch to fall in place under its
roller preparatory to a closing operation. If
the closing spring is not charged, the trip
latch is held, rotated clockwise until the
close spring is compressed as described in
Ch 3 Equipment Description, c. operAtIon,
1) Close Spring Charging. Electrically
initiated closing is blocked by the latch
checking switch (Figure 2, #47) when the
trip latch is not reset.
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8Equipment Description
Power/Vac® Electrical Ground and Test Devices
Equipped with ML-17 Mechansim
01.4IB.50100

1234 5
18
49
54
16
17
22
21 51
50
20 52
19
D
D
28
27
30
24 53
18
26
31
23
25
29
42
41
40
5
11
12
C
33
39
46
34
D
35
38
45
37
36 47
1. Rear Flywheel Section
2. Front Flywheel Section
3. Close Roller
4. Close Latch
5. Close Latch Monitor Switch
6. Closing Spring Assembly
7. Blocking Pin in Closing Spring Assembly
8. Hex Shaft with Connection Blocks on Flywheel
9. Wind Pawl
10. Slow Close Pawl
11. Wind Hub
12. Pawl Disengagement Cam Surface - On Frame
13. Pull Rod
14. Adjustable Throw Transfer Crank
15. Adjustment Link (Factory Adjustment Only)
16. Short Transfer Crank
17. Slotted Link
18. Trip Latch
19. Link - Trip Toggle to Frame
20. Link from Close Toggle to Trip Toggle
Figure 1 Typical Schematic for ML-17 Mechanism, Models -4
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Equipment Description
01.4IB.50100

Figure 2 Typical Schematic for ML-17 Mechanism, Models -4 (continued)
15
14
B
13
3210
C
44
49
43
9
8
43
1
6
7
A
48
A
2
21. Link from Output Crank to Close Toggle
22. Output Crank
23. Pole 1 Bell Cranks
24. Wipe Spring Trunnion Block
25. Interrupter Operating Rod Connection
26. Wipe Spring
27. Overtravel Stop Adjustment - On Each Pole
28. Horizontal Connecting Bar
29. Opening Spring Assembly
30. Opening Stop Block
31. Dashpot
32. Brake (on ML-17H Mechanism Only)
33. Closing Latch Shaft
34. Auxiliary Switch Drive Arm
35. Idler Link
36. Switch Drive Arm
37. Auxiliary Switch
38. Position Indicator Flag
39. Operation Counter
40. Spring Charge Indicator Arm
41. Rod
42. Spring Charge-Discharge Indicator Flag
43. Gear Motor Limit Switch
44. Gear Motor Limit Switch Operator
45. Gear Motor
46. Gear Motor Housing
47. Trip Latch Checking Switch
48. Slow Close Pin
49. Retaining Clamp
50. Opening Stop
51. Toggle Pin
52. Trip Roller
53. Horizontal Bar Stop Locking Nut
54. Trip Shaft
AA Eccentric Shaft Connecting Flywheel Halves
BB Hex Shaft Connecting Transfer Cranks
CC Flywheel Rotation Axis
DD Hex Shaft Connecting Output Cranks
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10 Equipment Description
Power/Vac® Electrical Ground and Test Devices
Equipped with ML-17 Mechansim
01.4IB.50100

1
2
10
34
7
8
9
6
5
a) Breaker Open-Close Spring Charged b) Breaker Closed-Close Spring Discharged
c) Breaker Closed-Close Spring Charged d) Breaker Open-Close Spring Discharged
1
2
10
34
9
86
5
7
1
2
10
34
9
8
6
5
7
1
2
10
34
9
8
6
5
7
1. Output Crank
2. Link-Output Crank to Close Toggle
3. Link-Close Toggle to Trip Toggle
4. Link Trip Toggle to Frame
5. Trip Latch
6. Slotted Link
7. Transfer Crank
8. Trip Roller
9. Linkage Return Spring
10. Toggle Pin
Figure 3 Toggle Linkage Positions of ML-17 Mechanism View from Rear
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Equipment Description
01.4IB.50100

4) Trip Free Operation
The linkage (Figure 1, #19 & 20 &
Figure 2, #21) is mechanically trip free in
any location on the closing stroke. This
means that energization of the trip coil
while closing after the auxiliary switch
contacts change position will rotate the
trip latch (Figure 1, #18) clockwise and
permit the ground and test device to
open. The linkage will reset as a normal
open operation, the flywheel will complete
its rotation, and the closing spring will
recharge as described under SPRING
CHARGING.
d. InterlockS
1) Closing Spring Discharge Interlock
The function of the closing spring discharge
interlock is to prevent racking into or out
of metal-clad switchgear a ground and test
device with the closing spring charged.
This is accomplished by a roller on the right
hand side of the mechanism which contacts
the racking mechanism and discharges the
closing spring except if the ground and test
device is in the “Disconnect/Test” position
or the “Connect” position in the
metal-clad switchgear. This interlock also
opens the CL/MS switch in the motor
charging circuit to prevent charging the
closing springs when the ground and test
device is between the “Disconnect/Test”
or “Connect” position in the metal-clad
switchgear.
2) Negative Trip Interlock
The function of the negative trip interlock
is to disengage the trip latch from the trip
latch roller thereby preventing a closing
operation. The interlock also opens the
latch checking switch (52LCS) in the
closing circuit thereby removing the close
circuit power. The negative interlock is in
operation while the ground and test
device is moving between the
“Disconnect/Test” position and the
“Connect” position. A redundant negative
trip interlock is a backup to the negative
trip interlock and provides the same
function except it operates only near the
connect position.
3) Positive Interlock
The positive interlock operates to prevent
the racking of a ground and test device
that is closed. A linkage connected to the
horizontal connecting bar extends a detent
bar out from the side of the mechanism
frame when it is in the closed position. If
the closed ground and test device is in the
“Connect” or “Disconnect/Test” position
in the metal-clad switchgear the detent
bar locks into the racking mechanism to
prevent access to the hex section of the jack
screw. The positive interlock also prevents
the lift truck from picking up a closed
ground and test device.
4) Closing Spring Gag Interlock
The closing spring gag interlock
(Figure 5) is provided on the ground and
test device to prevent a ground and test
device that has a gagged closing spring
from entering the metal-clad switchgear
unit. This is accomplished by projecting a
lever out of the left side of the mechanism
when the closing spring is gagged.
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12 Equipment Description
Power/Vac® Electrical Ground and Test Devices
Equipped with ML-17 Mechansim
01.4IB.50100

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Installation
01.4IB.50100
Ch 4 Installation
A. receIvInG
When the ground and test device is received
check for any sign of damage. If damage is
found or suspected, file all claims immediately
with the transportation company and notify
the nearest Powell representative.
The ground and test device is enclosed in
a carton used for shipment. The carton
is attached to the shipping pallet by two
metal bands. Remove the bands and lift the
carton from the pallet so that the ground and
test device is visible. Remove all shipping
hardware, members, or brackets that attaches
the device to the pallet. When these are
removed the ground and test device may
be removed from the shipping pallet. Refer
to Ch 4 Installation, B. HAndlInG, for more
information.
B. HAndlInG
After the ground and test device has been
removed from its shipping pallet it may be
rolled on its own wheels on a level surface. This
is the preferred way of handling the ground
and test device. When rolling the ground and
test device it should be pushed and steered by
the steel frame or the front cover.
Do not handle or move the ground and test
device by the primary disconnecting devices,
as damage may occur.
CAUTION
If necessary, the ground and test device can
be moved by a fork lift truck or an overhead
crane. When using a fork lift truck take care to
avoid components located under the ground
and test device floor pan. The device can also
be lifted by an overhead crane using the four
lifting points which have been provided for
hooks at the bottom of the ground and test
device mechanism housing (Figure 4).
Figure 4 Lifting Holes for Overhead Crane
a
b
a. Lifting Holes - Front (Top View)
b. Lifting Holes - Rear
c. StorAGe
Shipping and storage of electrical equipment
requires measures to prevent the deterioration
of the apparatus over a long unused period.
The mechanical and dielectric integrity must
be protected. Electrical equipment is designed
for use in a variety of environments. When
the equipment is in transit and storage, these
design considerations are not fully functional.
In general, the following measures must be
considered.

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14 Installation
Power/Vac® Electrical Ground and Test Devices
Equipped with ML-17 Mechansim
01.4IB.50100
1. Equipment designed for indoor installation
must be stored indoors in a climate
controlled environment to prevent
condensation of moisture. Exposure to rain
and the elements, even for a short period,
can permanently damage the equipment.
Space heaters within the equipment should
be energized, if so equipped. Humidity
controlling desiccant materials should
be utilized when space heaters are not
provided or cannot be energized. The
temperature should be kept above 33°F/1°C
and below 140°F/60°C. The relative
humidity should be kept below 60% or a
dew point of 15°C/59°F. The equipment
should be stored in such a manner as
to leave all doors and panels accessible
for inspection. The equipment must be
inspected on a routine basis to assure
operational integrity.
2. Equipment designed for outdoor exposure
may be stored either in indoor or outdoor
storage locations. The equipment must
be protected from airborne external
contaminates if stored outdoors. Outdoor
storage will also require additional care
to maintain temporary covers over
the openings and shipping splits. The
equipment must be provided with control
power to facilitate the energization of
space heaters, as well as other temperature
and humidity controlling equipment. The
temperature should be kept above freezing
(>33°F/1°C) and below (<140°F/60°C). The
relative humidity should be kept below
60% or a dew point of 15°C/59°F. The
equipment should be stored in such a
manner as to leave all doors and panels
accessible for inspection. The equipment
must be inspected on a routine basis to
assure its integrity.
d. SHIppInG poSItIon
The ground and test device has been shipped
in an open and discharged position. To
make sure close and open springs are in their
discharged position, press the manual close
button followed by pressing the manual trip
button.