SureSeT MV Metal-Clad Semi-Assembled Switchgear and EvoPacT MV Components5/15 kV, 1200/2000 A, 25/40 kAUL Recognized Components per ANSI/IEEE Standards Equipment and Component Integration Guide–Partner Offers – User Guide
NNZ9886700

Circuit Breaker Cradle

Circuit breaker cradle overview

An EvoPacT circuit breaker cradle is a separate, rigid, self-contained, bolted structure fabricated of heavy gauge steel which includes the essential items required in a switchgear circuit breaker compartment (see the figure Typical circuit breaker cradle assembly overview). EvoPacT circuit breaker cradles are intended to be used only with EvoPacT Medium Voltage Vacuum Circuit Breakers. An OEM may incorporate this circuit breaker cradle into the switchgear of their own design and construction. The EvoPacT circuit breaker cradle is a UL Recognized Component. Refer to Schneider Electric document NNZ9886800, SureSeT Medium Voltage, Metal-Clad, Indoor Switchgear User Guide for a detailed description of all circuit breaker cradle features and operational use. The Schneider Electric document JYT3013100, EvoPacT™ Medium Voltage Vacuum Circuit Breaker (VCB) should be used as a reference user guide for information on the circuit breaker used in this circuit breaker cradle.

As a standard, the circuit breaker cradle is designed for placement into a minimum of 26 inch (660 mm) wide OEM switchgear or existing field equipment. Consult with a Schneider Electric Services representative for use of the circuit breaker cradle in equipment wider than 26 inches (660 mm).

The core enclosure structure of the circuit breaker cradle is designed with a boundary width of 23.75 inches (603.25 mm) to help assist with:

  • OEM switchgear ventilation, electrical clearances, and wiring requirements and

  • potential retro-fills into existing equipment line-ups in customer field applications.

Bottom and rear support channels extend beyond the boundary of the core enclosure of the cradle to connect and mount the cradle to the switchgear equipment. Refer to Typical Circuit Breaker Cradle Top View with Minimum Required Mounting Locations, for an overview of dimensions.

The standard insulation used in the primary bushing assembly of the circuit breaker cradle is of a Group A material, but the primary bushing assembly may be of the Group B insulation material, if specified (refer to Schneider Electric document NNZ9886800, SureSeT Medium Voltage, Metal-Clad, Indoor Switchgear User Guide for further information on insulation material groups).

Typical circuit breaker cradle assembly overview

1 Core enclosure
2 Bottom support channels
3 Rear support channels
4 Shipping brackets
5 Primary bushing assembly
6 Ground bus assembly
7 Secondary disconnect receptacle for circuit breaker power and control
8 Low voltage receptacle for additional features (optional)
9 Mechanism-operated contacts (MOC) (optional)
10 Truck-operated contacts (TOC) (optional)
11 Space heaters (optional)
12

Lock-out/Tag-out (LOTO) provisions for Padlock/Keylock
DANGER
hazard of electric shock, explosion, or arc flash
  • The equipment must be installed, operated, and serviced only by qualified electrical personnel. Only qualified personnel familiar with medium voltage equipment are to perform work described in this set of instructions.
  • Store, install, and operate the electrical equipment only in the environment for which it was designed.
  • Perform work on the equipment only after reading and understanding all of the instructions contained in this and other associated user guides.
  • Use only Square-D EvoPacT circuit breakers with the EvoPact circuit breaker cradle.
  • Modifications to the cradle are not recommended and may cause incompatibilities with the breaker.
  • Do not apply excessive force that exceeds the withstand capability of the cradle during installation or while performing maintenance.
  • Do not install the breaker cradle into switchgear with insufficient clearances for flanges, wiring, and devices.
  • Ensure that all sub-assemblies required by the breaker cradle are installed properly.
  • Never insert a circuit breaker into a circuit breaker cradle that is not complete and functional.
  • Use only a circuit breaker cradle that is unmodified, complete, properly rated, and functional.
  • Handle this equipment carefully and install, operate, and maintain it correctly in order for it to function properly. Neglecting fundamental installation and maintenance requirements may lead to personal injury, as well as damage to electrical equipment or other property.
  • Observe the handling rules and avoid any shocks to the equipment.
  • Observe the normal service conditions described in this and other associated user guides.
  • Respect the storage conditions of the circuit breaker cradle.
  • Store the equipment in a clean, dry (including no condensation), well-ventilated area with an ambient temperature of approximately 70°F (21°C).
  • Never install the equipment if damaged.
  • Do not allow the ambient storage temperatures to exceed the specified limits.
  • For equipment that is not contained in enclosures, such as loose cradles, the storage environment must be temperature and humidity controlled.
  • Do not make any modifications to the equipment or operate the system with interlocks or barriers removed.
  • Contact the local Schneider Electric representative for additional instructions if the equipment does not function as described in this user guide.
  • Ensure that the breaker is properly aligned with the cradle before insertion.
  • Clean the equipment regularly to prevent a buildup of particulates on the equipment. For more details about maintenance schedule and cleaning intervals of time, refer to the Schneider Electric document NNZ988600, SureSeT Medium Voltage, Metal-Clad, Indoor Switchgear User Guide.
Failure to follow these instructions will result in death or serious injury.
DANGER
hazard of electric shock, explosion, or arc flash
  • If the cradle is used in a high pollution environment, follow the appropriate maintenance schedule per the Schneider Electric document NNZ988600, SureSeT Medium Voltage, Metal-Clad, Indoor Switchgear User Guide.
  • Do not expose the breaker and cradle assembly to electrical conditions outside the equipment ratings.
  • Do not store the equipment in a humid or highly gaseous environment.
  • Use only the racking handle supplied by Schneider Electric to rack in and out the circuit breaker.
  • Use only the tools recommended in this guide to install the circuit breaker cradle.
  • Do not use parts that are not approved or recommended by Schneider Electric in the equipment.
  • When racking the EvoPacT circuit breaker in and out, ensure that the racking status indicator is in the expected position when racking finishes.
  • Use only the SureSeT lift truck to install and remove EvoPacT circuit breakers from the circuit breaker cradle.
  • Protect the bushings during installation of the circuit breaker cradle and inspect for damage after installation.
  • Do not test or operate circuit breaker cradle interlocks by hand. Test interlocks only by moving the circuit breaker into or out of the compartment.
  • Do not attempt to operate interlocks in an incorrect sequence.
  • Properly close all bus joint boots before energizing this equipment.
  • Ensure that all tools and means to bypass shutter interlocks used during installation or maintenance are removed from the cradle once installation is complete.
Failure to follow these instructions will result in death or serious injury.

Mechanical connection points for circuit breaker cradles

During the assembly of equipment, use the provided mounting holes to secure the circuit breaker cradle in place. The circuit breaker cradle must be secured on the OEM switchgear to prevent any movement. Connection points to mount the cradle to the OEM switchgear are provided on the bottom of both sides of the cradle along the bottom support channels (see the figure Typical circuit breaker cradle right side view with minimum required connection point locations). Near the rear of the cradle, there are also required connection points on both sides on the rear support channels to mount the cradle into the OEM switchgear (see the figure Typical circuit breaker cradle right side view with minimum required connection point locations (left side similar)).The cradle top, front beam must also be secured by using a minimum of two (2) connection points at the top of the cradle (see the figure Typical circuit breaker cradle top view with minimum required connection point locations). Use 1/4-20 self-tap screws SAE Grade 5 (minimum) for all required connection hardware. Refer to the torque values in Torque Value. If required for integration into the OEM switchgear, the other holes on the top front and rear beams may be used, permitting that no hardware or OEM component interferes with operation of the circuit breaker cradle or the circuit breaker itself (see Additional top connection areas available).

DANGER
hazard of electric shock, explosion, or arc flash
  • Store the equipment in a clean, dry (including no condensation), well ventilated area with an ambient temperature of approximately 70°F (21°C).
  • Use only the tools recommended in this guide to install the equipment.
  • The cradle must be secured in the switchgear using all the required minimum connection points provided.
Failure to follow these instructions will result in death or serious injury.

Typical circuit breaker cradle right side view with minimum required connection point locations (left side similar)

Typical circuit breaker cradle top view with minimum required connection point locations

Additional top connection areas available

Tolerances for assembly

The connection points provided in the circuit breaker cradle have been designed with a tolerance value to assist in the correct assembly. From the connection points near the back side of the cradle to any connection point on another part, the maximum tolerance on the cradle is .250 inches (6.35 mm). For connection points located on the same part, the maximum tolerance is .03 inches (0.762 mm).

Tolerances between connection points

Floor straightness

To prevent the sheetmetal part on the cradle floor from flexing and to assist in the proper function for the mechanisms on top of the cradle floor, support the cradle floor within the OEM switchgear across the full width of the cradle in the area highlighted in green.

Electrical connection points for circuit breaker cradles

Primary bus

The circuit breaker cradle has six (6) stationary, primary, high voltage, line and load contacts for each phase housed in a primary bushing assembly. The rear of the contacts have a pad which allow the cradle to connect to the OEM switchgear primary bus (see Connection points for primary bus). Each pad has four (4) threaded holes which can be used to connect the OEM primary bus (see Stab connection points, for the bolt pattern). It is recommended to use a minimum of two (2) bolts per connection. Connect to cradle primary bus using 1/2-13 machine screws SAE Grade 5 (minimum). Refer to the torque values in Torque Value.

Typical polyvinyl chloride boots are supplied with the circuit breaker cradle to insulate the primary bus connection. Install the supplied boots over the contact pads and OEM switchgear primary bus. Close each boot with tie wraps. It is recommended that the OEM switchgear primary bus be designed to have these boots overlap with an epoxy insulation on the switchgear busbars. The busbar insulation and boots form an integral insulating system for the equipment to meet the dielectric ratings of the equipment. The insulating boots must be in place and properly closed before energizing the equipment.

DANGER
hazard of electric shock, explosion, or arc flash
  • Ensure bolts are torqued per the specifications in section, Torque Value.
  • Properly install and close all bus joint boots before energizing this equipment.
Failure to follow these instructions will result in death or serious injury.

Connection points for primary bus

Stab connection points

Ground bus

The circuit breaker cradle contains a provision to connect the cradle and circuit breaker to the OEM switchgear common ground system. The cradle ground bus connection is located on the rear of the cradle, extending out of the lower, left side. The dimensions for the ground bus cross section are 0.25 x 2.0 in. (6 x 51 mm). Connect to the circuit breaker cradle ground bus using 3/8-16 machine screws SAE Grade 5 (minimum). Refer to the torque values in Torque Value.

Connection points for ground bus

Secondary disconnect receptacle for circuit breaker power and control

The secondary disconnect receptacle for circuit breaker power and control is located above the circuit breaker in the front, center area of the compartment. Refer to Schneider Electric document NNZ9886800, SureSeT Medium Voltage, Metal-Clad, Indoor Switchgear User Guide for technical description and mounting.

DANGER
hazard of electric shock, explosion, or arc flash
  • When installing, inspecting, or maintaining the Secondary Disconnect Receptacle, follow the instructions provided in Schneider Electric document NNZ9886800, SureSeT Medium Voltage, Metal-Clad, Indoor Switchgear User Guide.
  • Use only the parts supplied by Schneider Electric and specified in this document.
  • The contacts and receptacles must be wired by Schneider Electric.
  • Use caution when aligning the breaker in the cradle. Misalignment between the breaker and cradle may cause damage to the secondary disconnect plug and receptacle.
Failure to follow these instructions will result in death or serious injury.

Low voltage receptacle for additional features (Optional)

The circuit breaker compartment may also be equipped with a stationary low voltage receptacle for additional features mounted to the rear, left side of the circuit breaker compartment floor. Refer to Schneider Electric document NNZ9886800, SureSeT Medium Voltage, Metal-Clad, Indoor Switchgear User Guide for technical description and mounting.

DANGER
hazard of electric shock, explosion, or arc flash
Failure to follow these instructions will result in death or serious injury.

Current transformers (CTs) (Optional)

The front-accessible, bushing/windows-type, 600 V rated, single- or multi-ratio current transformers can be mounted in the circuit breaker cradel around either the line or load primary high voltage contact bushing assembly insulating tubes. Further information on the CT’s can be found in the Schneider Electric document NNZ9886800, SureSeT Medium Voltage, Metal-Clad, Indoor Switchgear User Guide. Contact the local Schneider Electric representative for information on the purchase of CTs.

DANGER
hazard of electric shock, explosion, or arc flash
  • When installing, inspecting, or maintaining current transformers (CTs), follow the instructions provided in the Schneider Electric document NNZ9886800, SureSeT Medium Voltage, Metal-Clad, Indoor Switchgear User Guide.
  • Use only the CT’s specified by Schneider Electric.
  • Do not apply excessive force or torque during CT installation.
  • Use only the recommended tools and hardware to install the CT’s.
  • Ensure that all tools and means to bypass shutter interlocks used during installation or maintenance are removed from the cradle once installation is complete.
Failure to follow these instructions will result in death or serious injury.

Dimensions of a typical standard accuracy multi-ratio current transformer

For mounting a CT or set of CT’s against the threaded inserts on each bushing, use a minimum of two (2) 3/8 -16 x 4.5 inch or 8 inch long SAE Grade 5 (minimum) hex head bolts (length is determined by the CT configuration) each with a Belleville (conical) washer (0.4 inch ID x 0.88 inch OD). All CT mounting bolts should be torqued to 7–10 ft-lbs (9.5–13.5 N•m) and Loctite 242 Removable Strength applied to clean threads of each bolt and threaded insert on bushing assembly. DO NOT OVERTORQUE. If a CT must be removed or installed, hold the CT centered on the axis of the tube of the bushing and do not rest the weight of the CT on the tube of the bushing. To remove or install the CT, the cradle shutters will need to be fully open.

CT mounting

NOTE: Some parts of circuit breaker cradle not shown for clarity.

Mechanism-Operated Contacts (MOC) (Optional)

Mechanism-operated contacts are optional, circuit breaker cradle mounted, auxiliary contacts operated by the circuit breaker mechanism. Similar to circuit breaker mounted auxiliary contacts, they indicate whether the circuit breaker is in the open or closed position. The MOC can be configured to have either 10 or 13 contacts on the auxiliary switch. The auxiliary switch on the MOC in the cradle is provided unwired. They operate with the circuit breaker in both the connected and test/disconnected positions. Refer to the Schneider Electric document NNZ9886800, SureSeT Medium Voltage, Metal-Clad, Indoor Switchgear User Guide for technical description and mounting.

DANGER
hazard of electric shock, explosion, or arc flash
Failure to follow these instructions will result in death or serious injury.

Truck-Operated Contacts (TOC) (Optional)

Truck-operated contacts indicate the physical position of the circuit breaker in the cradle. They indicate whether the circuit breaker is in the connected or test/disconnected position. The TOC has 10 contacts on the auxiliary switch. The auxiliary switch on the TOC in the cradle is provided unwired. Refer to the Schneider Electric document NNZ9886800, SureSeT Medium Voltage, Metal-Clad, Indoor Switchgear User Guide for technical description and mounting.

DANGER
hazard of electric shock, explosion, or arc flash
Failure to follow these instructions will result in death or serious injury.

Space heater (Optional)

When heaters are specified by the customer, the circuit breaker cradle may be equipped with a HEATREX switchgear space heater, model number HX-565072. Heaters are mounted using 2x 1/4-20 self-tap screws SAE Grade 5 (minimum) torqued per the torque values shown in Torque Value.

Mounting of heater

Wire routing for circuit breaker cradles

DANGER
hazard of electric shock, explosion, or arc flash
  • Respect the boundary of the EvoPacT cradles for added switchgear parts.
  • Route the wires inside the defined wire routing shown. No wires are permitted within the envelope of the cradles.
  • When installing the wiring in the circuit breaker cradle, follow only the wire routing instructions and models provided by Schneider Electric in this guide.
  • Use only parts specified (or equivalent to) in this document.
  • Ensure the wires are routed only in the allowed areas and do not interfere with any mechanical parts on the breaker.
Failure to follow these instructions will result in death or serious injury.

Secondary disconnect receptacle for circuit breaker power and control

The secondary disconnect receptacle for circuit breaker power and control wire bundle should be secured using the pivot point on top of the wire tray that allows the receptacle to travel from the breaker connected position to the breaker test/disconnected position. Also, the wire bundle should be secured on the inside of the top channel and ran behind the automatic discharge plate to avoid any interference with the movement of the breaker. Ensure that the wire bundle is secured well enough to the OEM switchgear side sheet so that it does not intefere with the operation and movement of a circuit breaker automatic discharge pin through the path of the automatic discharge plate. It is recommended to use a similar restraining method as may have been done on the OEM switchgear side sheet for the TOC wire routing (see the figure TOC wire routing.)

Wire routing to secondary disconnect receptacle

NOTE: Some parts of circuit breaker cradle not shown for clarity.

Low voltage receptacle for additional features

The wire bundle of the low voltage receptacle for additional features should travel through the rectangular cutout in the mounting plate towards the rear of the cradle where it is secured on the slanted sheet metal floor part, then it is routed to the right side of the cradle. Use the provisions located under the right rail to secure the wire bundle, as it is routed to the front of the cubicle, and ensure that it avoids any interference with the movement of the breaker.

Wire routing to low voltage receptacle

NOTE: Some parts of circuit breaker cradle not shown for clarity.

Current transformers (CTs)

The wiring for the CT’s is not supplied or connected during manufacturing. It is recommended to use a minimum of 12 AWG to wire the CTs to the low voltage controls, but it is the responsibility of the OEM to properly connect and size the wiring according to the industry standards and specifications required by the OEM switchgear. Check all current transformer (CT) wires for loose connections and crimps. CT secondary terminal connections should have one brass plain washer, one bronze lock washer, and one brass nylock nut for each #8-32 brass stud. The nylock nut should be torqued to 18–21 in-lbs (2.0–2.3 N•m). DO NOT OVERTORQUE. Refer to the Schneider Electric document NNZ9886800, SureSeT Medium Voltage, Metal-Clad, Indoor Switchgear User Guide for further details about the CT’s.

The wire bundle of the CTs should pass through the wire trough with the provided cover installed to help keep the wire bundles in place. Use the path and cutouts on the sides to route the wire bundle to prevent blocking the path of the breaker and shutters. It is recommended to cover all wires with protective sleeving everywhere in the equipment except inside the low voltage compartment.

Wire routing of CTs

NOTE: Some parts of circuit breaker cradle not shown for clarity.

MOC and TOC

The wiring for the auxiliary switch on the MOC and TOC is not supplied or connected during manufacturing. It is recommended to use a minimum of 16 AWG to wire the MOC or TOC auxiliary switch contacts to the low voltage controls, but it is the responsibility of the OEM to properly connect and size the wiring according to the industry standards and specifications required by the OEM switchgear.

The wire bundle of the MOC and TOC should be routed and restrained close to the OEM switchgear side sheets to prevent blocking the circuit breaker. The MOC routing should be restrained close to the side sheet particularly where the circuit breaker MOC roller will pass by the wires, similar to the routing shown in the SureSeT switchgear passing behind a wire bracing bracket mounted on the switchgear side sheet (see the figure MOC wire routing.) The TOC routing should be restrained close to the side sheet particularly where the circuit breaker TOC and automatic discharge pins will pass by the wires, similar to the routing shown in the SureSeT switchgear passing behind the two wire bracing brackets mounted on the switchgear side sheet (see the figure TOC wire routing.) It is recommended to cover all wires with protective sleeving everywhere in the equipment except inside the low voltage compartment.

MOC wire routing

NOTE: SureSeT switchgear shown for reference example.

TOC wire routing

NOTE: SureSeT switchgear shown for reference example.

Space heater

The wiring for a space heater is not supplied or connected during manufacturing. The space heater must be wired by the OEM to power and a control device, such as a thermostat or humidistat, located in the OEM equipment. Provide power and wire the space heater according to the specifications of the heater manufacturer and OEM switchgear requirements. It is the responsibility of the OEM to properly connect and size the wiring according to the industry standards and specifications required by the OEM switchgear. The wiring from the space heater should be secured on the slanted sheet metal floor part, as it is routed to the right side of the cradle. Use the provisions located under the right rail to secure the wire bundle, as it is routed to the front of the cubicle, and ensure that it avoids any interference with the movement of the breaker.

Remote racking operations

DANGER
hazard of electric shock, explosion, or arc flash
  • Ensure that proper interlocking is applied to the circuit breaker racking mechanism motor control circuit
Failure to follow these instructions will result in death or serious injury.

It is responsibility of the switchgear manufacturer to ensure that proper interlocking and electrical control is applied to the racking mechanism motor. It is recommended to use a minimum of 16 AWG to wire the motor control circuit, but it is the responsibility of the OEM to size the wiring according to the standards and specifications required by the OEM switchgear. Refer to Schneider Electric document JYT3013100, EvoPacT™ Medium Voltage Vacuum Circuit Breaker (VCB) for further detailed circuit breaker information and a reference electrical schematic for a motorized racking mechanism in SureSeT switchgear.

The OEM must provide the following interlocking conditions as a minimum:

  • The racking mechanism motor operation ceases upon reaching the connected and test/disconnected positions.

  • The racking mechanism motor operation ceases upon the circuit breaker encountering an object that blocks it while racking.

  • The racking mechanism motor operation is prevented unless the circuit breaker is in the open position.

  • The racking mechanism motor operation is prevented in case a manual operation is ongoing or the racking/charging handle is inserted in its port.

  • The racking mechanism motor operation is prevented in case a locking condition (such as key lock or padlock activation) is applied.

  • In case the racking mechanism locking electromagnet is supplied, the racking mechanism motor operation is prevented in case the magnet is not powered on. The electromagnet indication contact shall be used for this interlocking function.

  • A switch is required on the switchgear doors of circuit breaker and auxiliary compartments equipped with motorized racking. The switch should be used to disconnect the racking motor power supply if the door to the compartment is open.

Provisions for ventilation of the circuit breaker cradle

The circuit breaker cradle requires an opening on the switchgear circuit breaker compartment door to allow for adequate intake of air for ventilation of the circuit breaker when in use. Blocking this area may impact the thermal performance of the equipment. The in-take for ventilation should be located in the lower front area of the cradle, highlighted in green in the figure Provisions for ventilation. Refer to the figure Typical SureSeT Metal-Clad Semi-Assembled Switchgear Configurations for the ventilation area used on SureSeT switchgear.

DANGER
HAZARD OF ELECTRIC SHOCK, EXPLOSION, OR ARC FLASH
The ventilation requirements specified in this guide must be followed during installation and while in use in the final switchgear.
Failure to follow these instructions will result in death or serious injury.

Provisions for ventilation

Provisions for keylock on the circuit breaker cradle

When specified on the order, the circuit breaker cradle allows for an optional keylock to be installed by the OEM. The keylock may be used to lock a circuit breaker out of the connected position. If required, the OEM must configure and order the keylock directly from a keylock supplier. The keylock provisions are designed to work with a KIRK Type “C” Camlock Isolation Interlock with M11 threads where the key is trapped when turned clockwise, such as KCAM00010 (see Drawing of Type C keylock). Refer to the instructions from the keylock manufacturer for information on application, operation, usage, installation, and maintenance of the keylock. The OEM should perform the following steps to assemble the keylock on the circuit breaker cradle:

  1. Assemble the keylock with the two (2) sheet metal parts provided (see Keylock sub-assembly).

  2. Apply grease on the edges of the sheet metal lever. Refer to the section Grease information.

  3. Use two (2) rivets to mount the keylock sub-assembly on the right-side positioning rail (see Keylock assembled on circuit breaker cradle).

    • Ensure the sheet metal lever extends into the cut-out on the moveable lockout plate.

    • Use 1/4 in. diameter steel rivets, such as the Avdel® 2761-0821 item, or equivalent strength fasteners to mount the sub-assembly.

  4. Verify the mechanism operates correctly, so that the following two (2) conditions are met:

    • When the key is turned fully in one direction, the lockout plate is held in the up position and the padlock hole aligns with the stationary latch plate, as shown in the figure Keylock assembled on circuit breaker cradle.

    • When the key is turned fully in the opposite direction, the lockout plate is able to fully lower.

Refer to the Schneider Electric document NNZ9886800, SureSeT Medium Voltage, Metal-Clad, Indoor Switchgear User Guide for further details.

Drawing of Type C keylock

Keylock sub-assembly

A Key (keylock component)
B Camlock cylinder (keylock component)
C Sheet metal mounting bracket
D Large nut (keylock component)
E Washer (keylock component)
F Sheet metal lever
G Small nut (keylock component)

Keylock assembled on circuit breaker cradle

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