Suggested Specifications
General
This specification and associated drawings describe Power-Style
QED-6
rear-connected switchboard assemblies listed
to UL 891.
Standards
QED-6 switchboards equipment shall be designed, tested, and manufactured according to the following standards.
| Standard | Description |
|---|---|
| UL 891 | Dead-front switchboards |
| NEMA PB-2 | Dead-front distribution switchboards |
Main and feeder circuit breakers used in QED-6 switchboards shall be designed, tested, and manufactured to the following standards.
Ratings
The ampacity of the low voltage switchboards shall be determined by the loading of the feeder circuits. Select the ampacity rating from the following table.
System Ampacity
| 1200 A | 3000 A |
| 1600 A | 4000 A |
| 2000 A | 5000 A |
| 2500 A | — |
The short-circuit current rating of the lineup shall be as specified on the drawings. All circuit interruption shall be accomplished by the circuit breaker and without the aid of limiter fuses. The circuit breaker short-time rating shall be as specified on the drawings.
Select the maximum ratings from the following table.
PowerPact D, H and J Circuit Breakers
| Service Voltage | Frame Size | ||
|---|---|---|---|
| 240 V | 480 V | 600 V | |
| 65 kAIR | 35 kAIR | 18 kAIR | 150–600 A |
| 100 kAIR | 65 kAIR | 25 kAIR | 150–600 A |
| 125 kAIR | 100 kAIR | 50 kAIR | 150–250 A (H, J) |
| 150 kAIR | 100 kAIR | 25 kAIR | 400–600 A (D only) |
| 600/347 Wye rating. | |||
MasterPact NW Circuit Breakers
| Service Voltage | Frame Size | ||
|---|---|---|---|
| 240 V | 480 V | 600 V | |
| 65 kAIR | 65 kAIR | 50 kAIR | 800–2000 A |
| 65 kAIR | 65 kAIR | 50 kAIR | 2500–5000 A |
| 100 kAIR | 100 kAIR | 85 kAIR | 800–3000 A |
| 100 kAIR | 100 kAIR | 85 kAIR | 4000–5000 A |
| 200 kAIR | 150 kAIR | 100 kAIR | 800–1600 A |
| 200 kAIR | 150 kAIR | 100 kAIR | 2000–3000 A |
| 200 kAIR | 150 kAIR | 100 kAIR | 4000–5000 A |
MasterPact NT Circuit Breakers
| Service Voltage | Frame Size | ||
|---|---|---|---|
| 240 V | 480 V | 600 V | |
| 50 kAIR | 50 kAIR | 35 kAIR | 800–1200 A |
| 65 kAIR | 50 kAIR | 50 kAIR | 800–1200 A |
| 100 kAIR | 65 kAIR | N/A | 800–1200 A |
| 200 kAIR | 100 kAIR | N/A | 800–1200 A |
The assembly is designed for use on 50 Hz or 60 Hz electrical systems up to 600 Vac. Any items not specifically mentioned, but necessary for proper operation are implied in this specification.
Products
Manufacturers
Low voltage rear-connected switchboards shall be Power-Style QED-6 switchboards using MasterPact NW, MasterPact NT, PowerPact D, H, and J circuit breakers by Square D.
Structure
General
-
Each steel section shall contain a circuit breaker compartment with one or more individual drawout circuit breaker(s), (and/or instrumentation compartments), plus a separate bus compartment and a rear compartment for incoming/outgoing cable connections.
-
A rigid, removable steel base channel shall be bolted to the frame to support the entire shipping section for moving on rollers and floor mounting.
- The finish shall be medium ANSI 49 gray.
Dimensions
-
Section widths shall be 22-inches, 30-inches, or 36-inches wide, depending on the size of the circuit breakers being installed.
-
The lineup shall provide adequate wire bending space for mains and feeder circuit breakers using up to 750 kcmil wires.
-
Section depth shall be 60-inches minimum when using 800 A feeders. If additional wire bending and/or conduit space is required, specify 72-inch or 80-inch deep sections.
-
Adequate conduit space shall be provided to allow all conductors to exit the structure at the same end.
Moving and Handling
-
The lineup shall be divided into shipping splits not to exceed 88-inches wide and shall be capable of being lifted overhead or by using a forklift.
-
Each shipping split shall be provided with removable lifting straps.
-
Removable base channels shall be provided with prying slots to facilitate final positioning of the lineup at the job site.
-
An overhead lifter or a floor-mounted lifter shall be provided to assist with the installation or removal of circuit breakers.
Circuit Breaker Compartment
Circuit Breakers
-
Each circuit breaker shall be mounted in its own barriered compartment.
-
Feeder circuit breakers rated 2000 A or less shall be capable of being mounted in the uppermost compartment without de-rating.
-
The front of the circuit breaker shall protrude through the door of the switchboard allowing access to the operational buttons, and/or the toggle mechanism.
-
All mains shall be two-step stored energy circuit breakers and shall allow for closed-door racking.
-
All circuit breakers shall be drawout or plug-in style construction.
-
Circuit breakers of like frame sizes shall be interchangeable as standard.
-
All prepared spaces shall be fully equipped for future devices, including the racking, drawout, or plug-in mechanism, bussing, and secondary contacts.
Secondary Connections
-
All customer secondary control and communications connections shall be front accessible.
-
A dedicated wiring trough compartment shall be accessible from the front to permit easy access to all control or communications terminations.
-
Control connections shall be either cage clamp or optional ring tongue terminals. All control wire shall be #14 gauge SIS.
-
Dedicated conduit entry for control wires shall be provided at the top and bottom of each section, capable of landing up to three 1 1/2- inch conduits and shall be front accessible.
Instrumentation
-
Where additional space is required for instrumentation, such as CPTs and metering, a barriered instrumentation compartment shall be provided.
-
The instrumentation compartment shall not inhibit the routing of control or communication wires.
Bus Compartment
-
All vertical and horizontal distribution bus shall be rated for the full ampacity of the lineup, up to a maximum of 5000 A. Tapered bus is not acceptable.
-
All bus joints shall consist of Grade 5 hardware and conical washers to withstand mechanical forces exerted during short circuits.
-
Plating shall be applied continuously to all bus work.
-
All bus bars shall be silver-plated copper.
-
All runbacks from the circuit breaker compartment to the cable compartment shall be insulated.
Cable Compartment
-
All incoming or outgoing power conductors shall be routed through this area.
-
Branch circuit breakers shall have adequate wire bending space, regardless of the circuit breaker interrupting rating.
-
The conduit area for each section shall be a minimum of 17-inches wide and provide adequate depth for all section conduits.
Barriers
-
Barriers shall be provided between the circuit breaker compartment and distribution bus compartment.
-
Barriers shall be provided between the circuit breaker compartment and the adjacent section.
-
Each circuit breaker shall be mounted individually in a barriered compartment. Full steel barriers shall be located at the top, bottom, and sides of the circuit breaker compartment.
Circuit Breakers and Trip Units
Circuit Breakers
-
Circuit breakers shall be MasterPact NW, MasterPact NT, PowerPact D, H and J circuit breakers by Square D listed to UL 489.
-
Circuit breakers shall be suitable for the specified short-circuit current rating without the use of external current-limiting fuses.
-
All circuit breakers or like frame size shall have field interchangeable electrical accessories, including shunt trip, auxiliary contacts, electrical operating mechanism, shunt close, and trip unit.
-
All secondary connections shall be terminated at the front of the circuit breaker cradle.
-
Each circuit breaker shall have built-in contact wear indicators.
Trip Units
-
All trip units shall be removable to allow for field upgrades.
-
Trip units shall incorporate “True RMS Sensing,” and have LED long-time pickup indications.
-
All trip units shall have the option to turn instantaneous to the OFF position.
The following table lists the standard and optional trip unit features. Select the appropriate trip unit(s) for the system performance desired.
MicroLogic Trip Unit Functionality
| Functions | Basic | Type A | Type P | Type H |
|---|---|---|---|---|
| True RMS sensing | X | X | X | X |
| LI trip configuration | X | X | – | – |
| LSI | O | O | X | X |
| LSIG/equipment ground fault trip | – | O | O | O |
| Equipment ground fault alarm (no trip) | – | – | X | X |
| Equipment ground fault trip and programming alarm | – | – | O | O |
| Adjustable rating plugs | X | X | X | X |
| LED – long–time pickup | X | X | X | X |
| LED – trip indication | – | X | X | X |
| Digital ammeter | – | X | X | X |
| Phase loading bar graph | – | X | X | X |
| Zone selective interlocking | – | X | X | X |
| Communications | – | O | O | O |
| LCD dot matrix display | – | – | X | X |
| Advanced user interface | – | – | X | X |
| Protective relay functions | – | – | X | X |
| Thermal imaging | X | X | X | X |
| Contact wear indication | – | – | X | X |
| Temperature indication | – | – | X | X |
| Incremental fine tuning of settings | – | – | X | X |
| Selective long-time delay bands | – | – | X | X |
| Power measurement | – | – | X | X |
| Waveform capture | – | – | – | X |
| Data logging | – | – | X | X |
| –
Not Applicable X Standard Feature O Optional Feature |
||||
Metering and Instrumentation
Main Metering
-
An optional PowerLogic™ PM 800, CM 3000 or CM 4000 Power Monitoring System by Square D shall be provided on the main circuit breaker when specified on the drawing.
-
CTs shall be sized appropriately for use on the main.
-
An optional low voltage Human Machine Interface and display shall be mounted on the same door as the main circuit breaker when specified on the drawing.
-
Optional input/output (I/O) and Ethernet communications card shall be provided when specified on the drawing.
Communications
-
Internal communications within the switchboard shall be Modbus.
-
Where specified, Transparent Ready equipment with an Ethernet gateway shall be located in the switchboard and accept inputs from the MicroLogic trip unit(s), PowerLogic PM 8, CM-3 or CM-4 circuit monitor(s), and Modicon™ PLCs.