WEG UBW400 User manual
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User’s Manual
WEG Molded Case Circuit
Breakers
UBW400
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WEG Molded Case Circuit Breakers - User’s Manual2
WARNING
Do not attempt to install or perform maintenance on equipment while it is
energized. Death, severe personal injury or substantial property damage
can result from contact with energized equipment. Always verify that no
voltage is present before proceeding with the task, and always follow
generally accepted safety procedures.
WEG is not liable for the misapplication or misinstallation of its products.
The user is cautioned to observe all recommendations, warnings and cautions relating
to the safety of personnel and equipment, as well as all general and local health and
safety laws, codes and procedures.
The recommendations and information contained herein are based on WEG
experience and judgment, but should not be considered to be all-inclusive or
covering every application or circumstance which may arise. If any questions arise,
contact WEG for further information or instructions.
1. INTRODUCTION
1.1. GENERAL INFORMATION
The UBW400 circuit breaker (Figure 1) are 600 V ac maximum rated. UBW400 circuit
breakers are listed in accordance with Underwriters Laboratories, Inc. Standard
UL 489 and satisfy the (P1) requirements of the International Electrotechnical Commission
Recommendations No. IEC 157-1.
Figure 1:
UBW400 circuit breaker frame
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WEG Molded Case Circuit Breakers - User’s Manual 3
2. INSTALLATION
The installation procedure consist of inspecting the circuit breaker and, as
applicable, installing the trip unit and rating plug, accessories, interphase
barriers, and terminals; mounting the circuit breaker; connecting the line and load
conductors; torquing terminals and attaching terminal shields. Circuit breaker
frames, trip units, rating plugs, accesories, mounting hardware, and unmounted
terminals may be supplied in separate packages. To install the circuit breaker,
perform the following steps.
1. Make sure that the circuit breaker is suitable for the intended installation by
comparing nameplate data with existing equipment ratings and system
requirements.Inspect the circuit breaker for completeness, and check for
damage before mounting. Uninstalled cover mounting hardware is supplied in a
plastic bag with the circuit breaker frame (see Figure 2 and Table 2).
Flat head, thread
forming screws
Pan head screws
Figure 2:
cover mounting hardware
3-pole
No. 8 x 1.88 in, Flat-head 6
.190 - 32 x 3.125 in, Pan-head 2
Table 2:
cover mounting hardware
2. Remove installed cover screws and cover.
NOTICE
The circuit breaker handle must be in the tripped or OFF position to remove the cover.
Instructions for installing the trip unit and accessories are supplied with the devices.
3. If not already installed, mount trip unit and accessories (if required) in circuit
breaker frame.
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WEG Molded Case Circuit Breakers - User’s Manual4
Caution
When removed and reinstalled, thread forming screws will try to reform
the threads in the base. Care should be taken every time a thread-forming
screw is used to ensure the screw starts in the original threads. Damaged
threads can result in improper circuit breaker cover retention.
4. Replace cover and install pan-head screws followed by thread-forming screws
as shown in Figure 3. Torque cover screws to 18-23 lb-in (2-2.6 N.m.).
5. If not already installed, mount terminals as shown in Figure 4. Secure the
terminals to the circuit breaker using a 7/32-inch socket wrench, and torque to
6-8 lb-ft (8-11 N.m). After mounting the circuit breaker and before installation
of the conductors, the terminal mounting screw can be checked or retightened
through the terminal when the conductor screw is removed. If warning label is
supplied with terminal, place on upper portion of circuit breaker cover.
11
1
3P 3P
3P
4P 4P
1
2
2 2
2
2
1
3P
4P
1
2
Figure 3:
cover screw installation positions
1. Screw, No. 8 x 1.88 inch, flat head, cross-recessed, thread forming.
2. Screw, No. 190-32 x 3.125 inch, pan head, cross-recessed.
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WEG Molded Case Circuit Breakers - User’s Manual 5
LT1UBW400 terminal
LT3UBW400 terminals
Conductor
screws
Terminal
mounting
screw
Terminal mounting screw
Circuit breaker terminal
conductors
Figure 4:
terminal installation
WARNING
The voltage in energized equipment can cause death or severe personal
injury. Before mounting the circuit breaker in an electrical system, make sure
there is no voltage present where work is to be performed. Special attention
should be paid to reverse feed applications to ensure no voltage is present.
NOTICE
Depending on the equipment configuration, the circuit breaker can be mounted using
different styles of hardware. The following steps describe how to mount the circuit
breaker using standard hardware. When special hardware is needed (for example,
with the electrical operator), the instruction leaflet describing the accessory also
describes the special mounting arrangements.
6. To mount the circuit breaker, perform the following steps:
a. For individual surface mounting, drill mounting panel using the drilling
plan shown in Figure 5. For panelboard mounting, only load end support
mounting holes are required. For deadfront cover applications, cut out cover
to correct escutcheon dimensions, see Figure 6.
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WEG Molded Case Circuit Breakers - User’s Manual6
Circuit breaker handle
3-pole breakers
Circuit
breaker
handle
1.719
(43.66)
.250-20 (M6-1.0) TAP
- 4 holes
.859
(21.82)
Figure 5:
circuit breaker mounting bolt drilling plans
Circuit breaker handle
Circuit breaker handle
Trip unit
Access area
.344R
(8.74)
.921
(23.39)
3.750
(95.25)
1.640
(41.66)
1.250
(31.75)
1.313
(33.35) 2.391
(60.73)
1.88R
(4.77)
2.625
(66.67) 4.782
(121.46)
Figure 6:
circuit breaker escutcheon dimensions for 3-pole circuit breakers
b. If circuit breaker includes factory or field installed internal accessories, make
sure accessory wiring can be reached when the circuit breaker is mounted.
c. Position circuit breaker on mounting surface.
NOTICE
Labels with accesory connection schematic diagrams are provided on the side of the
circuit breaker. A note should be made of the diagrams if the labels cannot be seen
when the circuit breaker is mounted.
d. Install circuit breaker mounting screws, washers, and nuts. Tighten screws
firmly, but do not exceed 28 pounds-inches (3 N.m).
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WEG Molded Case Circuit Breakers - User’s Manual 7
Caution
When aluminum conductors are used, the application of a suitable joint
compound is recommended to reduce the possibility of terminal overheating.
Overheating can cause nuisance tripping and damage to the circuit breaker.
NOTICE
When a dual conductor terminal (Catalog No. LT3UBW400) is installed on the circuit
breaker and a single conductor is used, the conductor should be installed in the terminal
opening nearest to the circuit breaker terminal mounting conductor.
7. Connect line and load conductors and accessory leads.
8. When step-type terminals (Cat. No. LT3UBW400) are used, terminal shields
(supplied with the terminals) must be installed on the circuit breaker (Figure 7).
Warning label supplied with the kit must be attached to the circuit breaker front
cover.
Mounting slots
Terminal cover
Dovetails
Figure 7:
terminal cover installation
9. If required, install terminal shield on circuit breaker cover with mounting screws
provided.
10. After the circuit breaker is installed, check all mounting hardware and terminal
connecting hardware for correct torque loading. Torque values for line/load
terminals are given in Table 3 and on the circuit breaker nameplate.
Terminal
cat. No.
Terminal
material
body
Screw
head type
AWG
wire
range
Metric
wire
range
Wire
type
Torque
value
lb-in (N.m)
LT1UBW400 Aluminum Socket 250-500 (1) 120-240 Cu/Al 375 (42)
Table 3:
cover mounting hardware
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WEG Molded Case Circuit Breakers - User’s Manual8
3. MANUAL OPERATION, AND THERMAL MAGNETIC
TRIP UNIT ADJUSTMENT
3.1. MANUAL OPERATION
Manual operation of the circuit breaker is controlled by the circuit breaker handle
and the PUSH-TO-TRIP but ton in the trip unit. The circuit breaker handle has three
positions, two of which are shown on the cover with raised lettering to indicate
ON and OFF. On the sliding handle barrier, ON, OFF, and trip are also shown by a
color-coded strip for each circuit breaker handle position: red for ON, white for
tripped, and green for OFF (see Figure 8).
Push-to-trip
Button
Thermal-magnetic
Trip unit adjustment
Button (3 places)
Handle position indicator
Color: Red
White
Green
On
Trip
Off (reset)
-
-
-
- On
On
Trip
Off
(Reset)
- Off
International
Symbols
Figure 8:
circuit breaker manual controls
3.2. CIRCUIT BREAKER RESET
After an automatic or accessory initiated trip, or a manual PUSH-TO-TRIP
operation, the circuit breaker is reset by moving the circuit breaker handle to the
extreme OFF position.
NOTICE
In the event of a thermal trip in a thermal magnetic type trip unit, the circuit breaker
cannot be reset until the thermal element in the trip unit cools. A circuit breaker with
an electronic type trip unit can be reset immediately.
No circuit breaker should be reclosed until the cause of trip is known and the
situation rectified.
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WEG Molded Case Circuit Breakers - User’s Manual 9
3.3. PUSH-TO-TRIP BUTTON
The PUSH-TO-TRIP button checks the circuit breaker tripping function and is
used to periodically exercise the operating mechanism in thermal-magnetic trip
units. The button is designed to be operated by a small screwdriver.
3.4. THERMAL-MAGNETIC TRIP UNIT ADJUSTMENT
The magnetic element of each pole of the trip unit can be adjusted by rotating the
adjustment buttons on the front face of the trip unit with a screwdriver. The buttons
have several settings as indicated on the nameplate with values in multiples of the
trip unit ampere rating (Ih) as shown in Figure 9. To adjust the setting, rotate
each button clockwise until arrow button points to desired setting.
Adjustment buttons
Figure 9:
trip unit magnetic adjustment buttons
4. INSPECTION AND FIELD TESTING
UBW400 molded case circuit breakers are designed to provide years of almost
maintenance-free operation. The following procedure describes how to inspect
and test a circuit breaker in service.
4.1. INSPECTION AND FIELD TESTING
Circuit breakers in service should be inspected periodically. The inspection should
include the following checks 1 through 8.
WARNING
The voltages in energized equipment can cause death or severe personal
injury. Before inspecting the circuit breaker in an electrical system, make sure
there is no voltage present where work is to be performed. Special attention
should be paid to reverse feed applications to ensure no voltage is present.
Caution
Some commercial cleaning agents will damage the nameplates or molded
parts. Make sure that cleaning agents or solvents used to clean the circuit
breaker are suitable for the job.
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WEG Molded Case Circuit Breakers - User’s Manual10
1. Remove dust, dirt, soot, grease, or moisture from the surface of the circuit
breaker using a lint-free dry cloth, brush, or vacuum cleaner. Do not blow
debris into circuit breaker. If contamination is found, look for the source and
eliminate the problem.
2. Switch circuit breaker to ON and OFF several times to be sure that the
mechanical linkages are free and do not bind. If mechanical linkages are not
free, replace circuit breaker.
3. With the circuit breaker in the ON position, press the PUSH-TO-TRIP button
to mechanically trip the circuit breaker. Trip, reset, and switch circuit breaker
ON several times. If mechanism does not reset each time the circuit breaker is
tripped, replace the circuit breaker.
4. Check base, cover, and operating handle for cracks, chipping, and discoloration.
Circuit breakers should be replaced if cracks or severe discoloration is found.
5. Check terminals and connectors for looseness or signs of overheating.
Overheating will show as discoloration, melting, or blistering of conductor
insulation, or as pitting or melting of conductor surfaces due to arcing. If
there is no evidence of overheating or looseness, do not disturb or tighten
the connections. If there is evidence of overheating, terminations should be
cleaned or replaced. Before re-energizing the circuit breaker, all terminations
and cable should be refurbished to the condition when originally installed.
6. Check circuit breaker mounting hardware, and tighten if necessary.
7. Check area where circuit breaker is installed for any safety hazards, inlcuding
personal safety and fire hazards. Exposure to certain types of chemicals can
cause deterioration of electrical connections.
4.2. FIELD TESTING
Any field testing should be done in accordance with applicable NEMA Standard.
The instructions for installation, testing,maintenance, or repair herein are provided
for the use of the product in general commercial applications and may not be
appropriate for use in nuclear applications. Additional instructions may be available
upon specific request to replace, amend, or supplement these instructions to
qualify them for use with the product in safety-related applications in a nuclear
facility.
The information, recommendations,descriptions,and safety notations in this
document are based on WEG’s experience and judgment with respect to Retrofitting
of Power Breakers. This instructional literature is published solely for information
purposes and should not be considered all-inclusive.If further information is
required, you should consult an authorized WEG sales representative.
The sale of the product shown in this literature is subject to the terms and conditions
outlined in appropriate WEG selling policies or other contractual agreement
between the parties. This literature is not intended to and does not enlarge or add
to any such contract. The sole source governing the rights and remedies of any
purchaser of this equipment is the contract between the purchaser and WEG.
NO WARRANTIES, EXPRESSED OR IMPLIED, INCLUDING WARRANTIES
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