Design Approaches for Hospital Distribution Systems With Considerations for Future Expansion, Operator Safety, and Cost

Transcription

1 Design Approaches for Hospital Distribution Systems With Considerations for Future Expansion, Operator Safety, and Cost Adam T. Powell, PE President Emerald Engineering, Inc. Jeffrey L. Small, Sr. Senior Specification Engineer GE Industrial Solutions October 12, 215

2 Quick Rundown: Selective Coordination: The Basics Arc Flash: The Basics Coordination vs. Arc Flash Who Wins & Why? Opportunities for Compromise System Growth Over Time What Can We Do? Equipment Selections & Specs Selectivity & Equipment Limitations Design Rules of Thumb Simple System Examples Things to Remember A Vendor s Perspective Frequent Oversights & Considerations

3 Selective Coordination: The Basics Concepts Regions of the Curve / LSI Thermal Magnetic LV Fuses Generators GFI Transformers Motors

4 Example #1: Basic Concepts

5 Example #2: Curve Regions / LSI

6 Example #3: Thermal Magnetics

7 Example #4: LV Fuses

8 Example #5: Simple Genset

9 Example #6: Ground-Fault

10 Example #7: Dry-Type Transformer

11 Example #8: Motors

12 Arc Flash: The Basics Concepts Personal Protective Equipment (PPE) NFPA 7E Incident Energy Mitigation Methods

13 Arc Flash: The Basics An Arc Flash occurs during a fault, or short circuit condition, which passes through this arc gap. The Arc Flash can be initiated through accidental contact, equipment which is underrated for the available short circuit current, contamination or tracking over insulated surfaces, deterioration or corrosion of equipment and, or parts, as well as other causes. An Arc Flash event can expel large amounts of deadly energy. The arc causes an ionization of the air, and arc flash temperatures can reach as high as 35, degrees Fahrenheit. This is hotter than the surface of the sun. -GE Industrial Solutions

14 Before:

15 After:

16 Example #9: Simple 1-Line

17 Personal Protective Equipment (PPE)

18 Incident Energy Incident Energy measured on a surface at a specified working distance from the arc flash location Measured in cal/cm 2 Factors include: Available Fault Current System Impedance Protective Device Settings & Clearing Times

19 Coordination vs. Arc Flash: Who Wins, and Why? Selective Coordination Often Comes at the Expense of Arc Flash Hazard. Short Time, Short Time Delay, and Instantaneous Settings Drastically Impact Incident Energies at the Buss(es) Downstream of the Protective Device. Tendency to Set Breakers to Max in Healthcare Applications As long as it coordinates Limiting the Impact of a Fault and Clearing it are Priority What are the Implications? Is there a Middle Ground? Revisiting Example #9

20 Example #9: Simple 1-Line

21 Example #9 Labels

22 Example #1: Revised Settings

23 Example #1 Labels

24 System Growth Over Time What Can We Do? System Sprawl What can Design Professionals do to Limit the Cost, Safety, and Reliability Impact of Future Renovations? Gear Provisions that Make Sense Specify Exactly What You Want Leave Room to Coordinate Design Rules of Thumb for LSI & Thermal Mag Leave Room to Limit Arc Flash Hazard

25 Gear Provisions that Make Sense Subfeed Lugs Front-Hinged Door Adequate Lug Sizes Inadequate Lug Sizes Frequently don t Present Until Submittals or Later Often too Late Contractors: Make the Vendor Own the 1- Line in Addition to the Panel Schedules and Specs. Sufficient Prepared Space for Future

26 Specify Exactly What You Want Gear Type: Switchgear Switchboard Distribution Panelboard Lighting/Appliance Panelboard Breaker Types LI/LSI/LSIG Thermal Mags Specific Types Coordination Study on the Documents

27 Panel Schedule #1: "N3L" 12/28V. 3PH, 4W 6A MLO NEMA-1 22, AIC COPPER BUS MFR: GE VOLTAGE/PHASE 6A BUS SURFACE FULLY RATED SOLID NEUTRAL CKT AMPS POLE DESCRIPTION NOTES LOAD VA CKT AMPS POLE DESCRIPTION NOTES PANEL N3L PANEL N3L PANEL N3L PANEL N3L SPACE CHILLER MRI SPACE 22 SPACE SPACE 28 SPACE SPACE 34 SPACE SPACE 4 SPACE LOAD CONNECTED DEMAND DEMAND NOTES: DESCRIPTION LOAD (VA) FACTOR LOAD (VA) 1. LIGHTING HVAC - COOL HVAC - HEAT RECEPTACLE MISC TOTAL TOTAL DEMAND 3PH 242.AMPS LOAD VA

28 Panel Schedule #2: "N3L" 12/28V. 3PH, 4W 6A MLO NEMA-1 22, AIC COPPER BUS SOLID NEUTRAL GE: SBO VOLTAGE/PHASE 6A BUS SURFACE FULLY RATED HINGED DOOR CKT AMPS POLE DESCRIPTION NOTES LOAD VA CKT AMPS POLE DESCRIPTION NOTES LOAD VA PANEL N3L1 SEHA PANEL N3L3 SEHA PANEL N3L2 SEHA PANEL N3L4 SEHA SPACE CHILLER MRI SEHA SPACE SPACE SPACE SPACE SPACE SPACE SPACE SPACE SUB FEED 6 3 LUGS LOAD CONNECTED DEMAND DEMAND NOTES: DESCRIPTION LOAD (VA) FACTOR LOAD (VA) 1. LIGHTING HVAC - COOL HVAC - HEAT RECEPTACLE MISC TOTAL TOTAL DEMAND 3PH 242.AMPS

29 Leave Room in the System to Coordinate - Now and in the Future LSI : LSI 1.5 : 1 ratio Upstream : Downstream LSI : Thermal Magnetic 2 : 1 ratio Upstream : Downstream Thermal Magnetic : LSI 2 : 1 ratio Upstream : Downstream Thermal Magnetic : Thermal Magnetic (Distribution Panelboards) 2 : 1 ratio Upstream : Downstream Thermal Magnetic : Thermal Magnetic (Branch Panelboards) 5 : 1 ratio Upstream : Downstream

30 Leave Room in the System to Coordinate - Now and in the Future 15kVA Dry-Type Transformers Sometimes Useful but Items to Consider: 6A Secondary MCB Panelboard will have 1A or 125A Buss Cost Difference with 3kVA is Negligible Primary and Secondary Conductors have Negligible Cost Difference with 3kVA Primary & Secondary Most Manufacturers can Coordinate, but Limits Branch Breaker Sizes to Almost Exclusively 2A Plan on Dry-Types 45kVA or Less Being Last Level No Feeder Breakers Downstream

31 Simple System Examples

32 Simple System Examples

33 Example: LNA1

34 Example: HNDP

35 Example: LSLA

36 Example: LSHDP

37 Example: EQHDP

38 Example: CLA2

39 Example: CHDP

40 Example: MSB

41 Example: Genset

42 Example: GFI

43 Example: Arc Flash Analysis

44 Example: Arc Flash Analysis

45 Frequent Oversights & Considerations Compliance with NEC B.5 Vertical Segregation of Required/Optional Emergency Loads Automatic Transfer Switches - Close and Withstand Rating Only not Interrupting If Switchgear/LVPCB are Utilized: 3-Cycle Transfer Switches Required How Shall We Comply with NEC ? Avoid MLO Service Entrance Equipment System Origin: 3-Pole or 4-Pole ATS s Existing Conditions

46 Frequent Oversights & Considerations A Generator Submittal is not Complete without the Following: Generator Thermal Damage Data Generator Decrement Curve Data Generator Internal Thermal Overload Relay Data (if applicable) Generator OCPD Data Alternator Performance Data Consider the Impacts of: Paralleled Generators and Available Fault Current, Arc Flash Incident Energy, etc.

47 Frequent Oversights & Considerations Selective Coordination Considerations: Impacts of Generator MCB Settings, when Appropriately Applied, on Coordination Downstream Coordinate Normal Feed to ATS on ALL Facilities (Nursing Homes, etc.) OCPD Interrupting Rating Consider Zero Sequence Current Importance of Modeling Large Motor Contributions Generator OCPD AIC may Require De-rating per IEEE Blue Book 3.29 To Calculate Generator X/R: X/R = (2π)(f)(Ta)

48 Frequent Oversights & Considerations VFD Application from Generator Source: Restart from Power Loss Only LOTO Procedures Load Harmonic Content Bypass No Motor Contribution

49 End.