TECHNICAL SPECIFICATION
ENGINEERED POWER DISTRIBUTION SYSTEM (PDU)

 

1.0        SCOPE

1.1        The System
           
This specification covers the electrical characteristics and general requirements for AC low voltage power distribution equipment, hereafter referred to as the EPDS (Engineered Power Distribution System) PDU, UPS, STS.  The EPDS is designed primarily for distribution, monitoring and isolation of electrical power and will properly interface with the AC power source for critical loads within a data center environment.

2.0        APPLICABLE STANDARDS, AGENCY APPROVAL AND REFERENCES

The following standards and documents apply to the specified equipment to the extent defined herein:

• FCC Part 15 Class A (47 CFR 0-19)                               

2.2        2.3        UL / ULc standard 891
2.4        NEMA Standard ST-1
2.5        NEMA ST20 - Dry-Type Transformers for General Applications
2.6        NEMA AB1 - Molded Case Circuit Breakers
2.7        NEMA PB1 - Panelboards
2.8        NEC (NFPA70) Section 645Code
2.9        ISO 9000 - International Organization for Standardization

 

3.0        SYSTEM DESCRIPTION AND OPERATION

3.1        Normal Operation

Under normal operation the input power is routed through the Main Input Circuit Breaker which applies and disconnects AC power to the unit and protects the system in the event of a power overload.  Power is directed to the isolation transformer where it will be electrically isolated on the output side of transformer.  A monitoring system placed on the output of the transformer will monitor the output power and trigger an alarm in the event of a power quality deviation. Output power is fed to the respective panel boards and / or distribution breakers to distribute power to specific loads.  Load circuits can be controlled manually from distribution panelboards. This product is used in conjunction with PDU, UPS, uninterruptible power supply, Twinsource rack mount static transfer switch, STS, medical UPS, medical grade UPS, medical power conditioner, medical grade power conditioner, enterprise UPS and water detection system.

3.2        Emergency Operation

An EO (Emergency Off)  switch shall be provided. This shall be a momentary, push-button switch with a protective cover that shall prevent accidental operation. This product is used in conjunction with PDU, UPS, uninterruptible power supply, Twinsource rack mount static transfer switch, STS, medical UPS, medical grade UPS, medical power conditioner, medical grade power conditioner, enterprise UPS and water detection system. It shall be illuminated by a red replaceable LED. When activated, the EPO will shunt trip the main input circuit breaker.

4.0        REQUIREMENTS AND PERFORMANCE CHARACTERISTICS

4.1        Ratings

The Power rating of the EPDS shall be rated 100 kVA.

4.2        Input Requirements

4.2.1     The input voltage of the EPDS shall be 480 V+/- 15%, 3 Phase, 3 Wire plus Ground.

• Input Frequency shall be 60 Hz.

 

4.3        Output Characteristics

• Nominal Output Voltage shall be 208 V +/-15%, 3 Phase, 4 Wire plus Ground
• Nominal Output Frequency shall be 60 Hz.

4.3.4     Harmonic Distortion, Voltage:    < 1% (maximum induced by transformer)
4.3.5     Efficiency at full kW load:          > 97%

4.4        Environmental Conditions

4.4.1     Temperature:
Operating:                     -10°C to +40°C
Storage:                       -40°C to +60°C

• Relative Humidity:                    

Operating:                     10% to 90% non-condensing
Non-operating:              10% to 70% condensing

4.4.3     Altitude (Above Sea Level):       
Operating:                     -500 to 7,000 feet
Non-operating               -500 to 25,000 feet

Audible Noise:  Typical, average noise level, ‘A’ weighted at three feet from the front of the cabinet at no load.

55dB:                           50 kVA to 300 kVA

 

5.0        FUNCTIONAL DESCRIPTION

5.1        Main Input Circuit Breaker

The EPDS shall be equipped with a main input circuit breaker (CB1) which, when closed and fed by a voltage source, energizes the EPDS. This product is used in conjunction with PDU, UPS, uninterruptible power supply, Twinsource rack mount static transfer switch, STS, medical UPS, medical grade UPS, medical power conditioner, medical grade power conditioner, enterprise UPS and water detection system.  The circuit breaker provides internal thermal overcurrent and instantaneous short circuit protection. The circuit breaker (CB1) includes a 24Vdc shunt trip to automatically open the circuit breaker and disconnect power to the entire unit when the Emergency Power Off (EPO) or remote EPO is activated, or when a designated alarm occurs.

The Main input circuit breaker is manually operated, automatic trip, rated for 600 VAC, 60 Hz, 3 Phase, and rated not less than 125% of the EPDSs full load input current rating.  It shall carry the manufacturer’s standard interrupting capacity for that rating.  This product is used in conjunction with PDU, UPS, uninterruptible power supply, Twinsource rack mount static transfer switch, STS, medical UPS, medical grade UPS, medical power conditioner, medical grade power conditioner, enterprise UPS and water detection system.
High interrupting capacity ratings shall be available at 222 KAIC for 480V systems.  Higher ratings are also possible.  The ‘On (1)’ and ‘Off (0)’ positions shall be clearly marked.  The CB will provide internal thermal/magnetic over current and instantaneous short circuit protection in each pole. Phase polarities shall be clearly marked.

 

5.2        Power Monitoring

The EPDS will include an advanced Circuit Monitor system monitor for metering and display of the EPDS output parameters. The monitor shall display the output / load side voltage, current, kVA, kW and frequency and other parameters defined in 5.2.1. All measured values will be displayed on a large format LCD display mounted on the front of EPDS. The meter shall also be equipped with LED alarm status indication.  This product is used in conjunction with PDU, UPS, uninterruptible power supply, Twinsource rack mount static transfer switch, STS, medical UPS, medical grade UPS, medical power conditioner, medical grade power conditioner, enterprise UPS and water detection system.

 

           

• Metering:

All metered values will be in "true RMS" values with 0.35% accuracy.  The monitor shall include a keypad allowing for the viewing of different selected values. The monitor shall display the following values and alarm conditions:

5.3        Controls and Communications:

The user shall be able to control and communicate with the EPDS via the following interfaces:

• Emergency Off (EO) button that when activated shall trip the AC input circuit breaker with shunt trip
• Audible Alarm
• Dry contact form C relay located on the Circuit Monitor and activated by any condition listed in section 5.4
• RS232 and RS485 serial communications interface using ModBus Protocol
• Ethernet via HTML web pages (when specified as an option)

                                   

5.4        Indicators:

The EPDS provides audible and visual alarm indication of abnormal conditions.  Upon activation of selected alarms, the EPDS sounds an audible alarm and activates an alarm LED.  The alarm sounds until an operator presses the “Audible Alarm Silence” button.  The reset button silences all existing alarms. This product is used in conjunction with PDU, UPS, uninterruptible power supply, Twinsource rack mount static transfer switch, STS, medical UPS, medical grade UPS, medical power conditioner, medical grade power conditioner, enterprise UPS and water detection system. Upon activation of the same or a new alarm, the audible alarm will sound again.  The audible alarm will be activated only by selected alarm conditions with thresholds factory programmable and stored in non-volatile memory.  Factory setting shall be as follows:

                        Output Overvoltage:                              +10%
Output Undervoltage:                            -13%
Transformer Overtemperature:                Alarm at 180°C: alarm shut down at 195°C
Overload (overcurrent):
Each Phase:                                         110%
Neutral:                                                 165%
Phase Loss (output Voltage)                  25% of nominal phase-to-neutral
Voltage Unbalance:                               15% deviation, one phase from average
Watts, VAR, VA:                                   110% of nominal
Frequency:                                            +/- 5hz

The “Transformer Core Temperature Warning” LED’ shall illuminate upon a transformer over-temperature of 180° C.

5.5        Main Isolation Transformer

The main isolation transformer is provided as a standard feature.  The output rating of the transformer shall be the same as the continuous duty maximum full load rating of the EPDS.  The isolation transformer is a NEMA ST20, factory-assembled, dry type, double shielded isolation transformer with 200% rated neutral. This product is used in conjunction with PDU, UPS, uninterruptible power supply, Twinsource rack mount static transfer switch, STS, medical UPS, medical grade UPS, medical power conditioner, medical grade power conditioner, enterprise UPS and water detection system.  Each phase of the transformer is a three-wire DELTA connected input winding and four-wire WYE connected 208Y/120 VAC output winding.    The isolation transformer character characteristic are described below:

K-Factor:                      K-13
Windings:
Filament:                       Copper
Harmonic Distortion:      less than 1%
Efficiency:                    greater than 96.5%%
Insulation system:         240°C, with 150°C winding temperature rise
Impedance:                   3% to 4.5% at rated load
Basic impulse level:       10kV
Common mode:            -120db,10Hz to 1Mhz
Normal mode:               20db per decade
Ventilation:                    Convection cooled.
Taps:                            Taps shall use copper bus bar and shall be welded to the filament. The use of “hooked” wire taps shall be prohibited. Compensation taps are provided on the primary windings to allow field adjustment for either low or high source voltages as follows:

FCAN = Full capacity above normal (taps): 2.5%, 5.0%

FCBN = Full capacity below normal (taps): 2.5%, 5.0%, 7.5%, 10%

               
Bus Connections:          All bus connectors shall be solid copper bus bar with welded connections to the filament.

Temperature Sensors:    Two thermal switches are wound into each coil "hot spot’. The
switches are normally-open contacts. The switches are wired to a terminal block mounted inside the cabinet. At 180°C the first contact closes and causes an LED to illuminate and an audible alarm to turn on at the status panel. This product is used in conjunction with PDU, UPS, uninterruptible power supply, Twinsource rack mount static transfer switch, STS, medical UPS, medical grade UPS, medical power conditioner, medical grade power conditioner, enterprise UPS and water detection system.At 195°C the second contact closes causing the main input circuit breaker to trip.  An LED will illuminate and an audible alarm will turn on at the status panel.

5.6        Circuit Breakers and Panelboards

The EPDS is provided with two output distribution panel boards providing a total of 84 pole positions, each with the following characteristics and/or features:

• Branch Circuit Panel Board:

 

NEMA PB1, Square D type Universal (Plug-in or Bolt-on) NQOM442L225CUNLB
Panel board accepting QOB or QOB-VH bolt-on (standard), plug-in (QO) circuit breakers.

Pole Capacity:              42 poles, capable of accepting 1, 2, 3-pole circuit breakers
Buss Rating:                 225 Amperes
Copper Ground bus:      42 terminals
Copper Neutral Bus:      Rated for 200% of nominal phase current (450 Amps)

The panel board shall accommodate up to 100Amp CBs and can be mounted based on available panel board cable bending space.

• Panel board Main Breaker:

 

The EPDS has one panel board main circuit breaker per 42 pole distribution panel board (described below). The panel board main CB provides thermal/magnetic overload and short-circuit protection for each panel board, and allows manual on/off control.

Each panel board is protect by a main circuit breaker.

Rating:                          225 Amperes
Interrupting Capacity:     22,000 AIC ( 10.000 AIC for 380 V models)
Voltage Rating:             240 VAC maximum (415VAC maximum for 380 V models)
Model Type:                  Q2 (For 380V: SQL)

 

5.7        Grounding

Construction:    A main grounding bus bar is provided and is effectively bonded to the unit frame.
A ground busbar is installed in all cabinets.

Identification:    All ground connections use copper conductors with green insulation or green
marking where required.

Connections:                 The following points are connected to ground:
Isolation transformer neutral
Isolation transformer shields and core
Primary input cable ground (when provided with jbox)

Panel Board Ground Bus:          Ground bus located below (or above for top entry) the panel
board, with wire connections for up to 42 wires. Lug range is 4 to 14AWG. Ground bus is provided for easy access

 

6.0        MECHANICAL DESIGN

6.1        Enclosure

The EPDS is housed in a free standing data center grade server rack with dead front construction designed for installation on a raised or a flush floor. This product is used in conjunction with PDU, UPS, uninterruptible power supply, Twinsource rack mount static transfer switch, STS, medical UPS, medical grade UPS, medical power conditioner, medical grade power conditioner, enterprise UPS and water detection system. The EPDS can accommodate bottom or top feed cables. The system monitor panel, input and output circuit breakers, and all customer power and control connection points are accessible from the front or side of the EPDS. All circuit breakers are protected with "hinged dead front" panels to prevent access without a tool.  The EDPS shall have hinged and latched steel doors on the front and rear of the unit. The doors shall have an acrylic window to provide visibility of the circuit breakers.

The cabinet is mounted on heavy-duty casters with leveling jacks. 
Exterior Color shall be black or a custom color shall be offered as an option.

Exterior and interior sheet metal is 16 gauge or better.  Exterior, use 10-32 Truss head S/S with locking patch screws mounted with x nylon washers. Interior, use rivets & monobolts where possible, all others use MGE’s standard hardware

Outside painted panels are interlocked.

Panelboard dead front covers are hinged on all cabinets to provide easy access when changing branch circuit breakers or performing infrared heat scans. Panelboard dead front covers are also adjustable for proper alignment and shall be powder coated to match the cabinet exterior.  All hardware for accessing dead front covers shall utilize captive quarter turn screws. This product is used in conjunction with PDU, UPS, uninterruptible power supply, Twinsource rack mount static transfer switch, STS, medical UPS, medical grade UPS, medical power conditioner, medical grade power conditioner, enterprise UPS and water detection system.

 

The panelboards shall be mounted so that two panelboards are accessible from the front of the unit and two via the rear or the unit.

• Casters

 

The cabinet shall be mounted on four (4) heavy duty casters. The casters rotate 360º. The casters are sized to support the maximum weight of the EPDS without damage to surfaces or bearings. This product is used in conjunction with PDU, UPS, uninterruptible power supply, Twinsource rack mount static transfer switch, STS, medical UPS, medical grade UPS, medical power conditioner, medical grade power conditioner, enterprise UPS and water detection system. Casters will allow the EPDS to roll over normal surfaces without damage or hindrance. "Normal" surfaces include, but are not limited to, concrete slab, asphalt, wood, tile, etc.

• Leveling Jacks

 

Four leveling jacks are typically provided to support the maximum weight of the EPDS. Design allows the leveling jacks to be raised a minimum of one inch (1") to prevent damage during shipment.

• Center of Gravity

 

The design shall allow the EPDS to be tilted and moved up a 15° incline without tipping over.

• Access

 

The system monitor panel, input and output circuit breakers, and all customer power and control connection points are accessible from the both the front faces of the EPDS. The exterior doors are provided with a latched door lock (keyed lock optional).

• Lifting

 

The EPDS is designed to allow lifting the unit using a forklift.

• Maintenance

 

Maintenance can be accomplished without the need for a special tool (other than a screw driver or crescent wrench) or fixture. Field replacement of any electrical component or assembly (other than the transformer) is achieved without lifting of more than 40 pounds (18 kilograms) of weight and without the use of hoists or jacks. This product is used in conjunction with PDU, UPS, uninterruptible power supply, Twinsource rack mount static transfer switch, STS, medical UPS, medical grade UPS, medical power conditioner, medical grade power conditioner, enterprise UPS and water detection system.The design allows for easy and safe replacement, adjustment or repair of all assemblies, subassemblies, modules, components, etc. A minimum of 36" may be required per local or national electrical codes in front of each panel board. 

 

6.8        Dimensions

The overall size of the EPDS is 82.0" high, 36.0" deep with a width of 36.0”  inches.

 

6.9        Weight

The weight of the EPDS shall be not exceed 1950 lbs with a 150 kVA transformer.

 

6.10      Ventilation & Heat Rejection

The EPDS is convection cooled.  Air access is from the bottom and exhausts from the top. 

 

6.12      Conduit Landing

The input conduit landing panel shall have three 2.0” inch knockouts located on the top and bottom input conduit plates. Each knockout can be punched to accept up to 3” conduits.  The panel board conduit landing panel shall have a combination of up to (84) concentric knockouts for ½” conduit and space for 20 larger knockouts.

There shall be an optional under floor conduit landing box that shall have a connecting wire tray to the EPDS to allow unprotected routing of output cables to the conduit box. This product is used in conjunction with PDU, UPS, uninterruptible power supply, Twinsource rack mount static transfer switch, STS, medical UPS, medical grade UPS, medical power conditioner, medical grade power conditioner, enterprise UPS and water detection system. The conduit box shall accommodate 168 ½” or ¾” conduit connections on the for sides of the box to simplify connectivity to output cable whips. 

6.13      Termination

All primary and secondary power wiring shall be suitably terminated using UL acceptable pressure (crimp) or screw-type lug assemblies. Belleville-type washers and lock washers shall be used on all associated studs or bolt-stacks. This product is used in conjunction with PDU, UPS, uninterruptible power supply, Twinsource rack mount static transfer switch, STS, medical UPS, medical grade UPS, medical power conditioner, medical grade power conditioner, enterprise UPS and water detection system.Control instrumentation, PC board, and interconnection wiring terminations shall conform to the UL standard.

Inductive Noise Coupling: Maximum separation shall be maintained between primary and secondary wiring and / or control/alarm wiring. To the extent possible, no primary or input wiring is permitted to share any area within the EPDS2 that is occupied by secondary wiring except within the main transformer compartment.

6.14      Power Wiring

All internal wiring shall be stranded copper with PVC, Neoprene or Silicon insulation with a minimum operating voltage of 600 volts RMS. All wires shall be appropriately marked UL and CSA recognized as being suitable for the application. Minimum insulation temperature rating shall be no less than 75º C, and in no case is less than that required by the location/application of the wiring.

6.15      Control Wiring

All control and instrumentation wiring used in this application shall be tinned, stranded copper with a temperature rating of at least 75º C. Insulation type is to be at least 125% of anticipated continuous load (3 hours or longer). Voltage rating is no less than required per UL and NEC. In areas where either primary or secondary AC voltages are present, PC board wiring and interconnect wiring will conform to the requirements of UL Standard 1950 for the application and location of the wiring.

 

10.0      WARRANTY

The EPDS shall be covered by a full parts and labor warranty from the manufacturer.  The warranty period shall be for twelve (12) months from date of installation and start-up or eighteen (18) months from date of shipment from the manufacturer, which ever occurs first.

 

11.0      QUALITY TESTING

Each unit shall have a formal quality testing procedure that documents the mechanical testing of each electrical connection, high potential testing, correct operation of subcomponents, transformer load and impedance testing, physical appearance and control wiring integrity. This documentation shall be provided with each unit.

 

12.0      APPROVED MANUFACTURER

The specified equipment shall be manufactured by ONYX Power Inc. or approved equal with 10 years or more experience in the manufacture of power magnetics and power distribution assemblies.