Technical Assignment #2 Electrical Systems Existing Conditions and Building Load Summary Report. Executive Summary

Transcription

1 Matthew Fracassini Lighting/Electrical Greenwich Academy Upper School Greenwich, CT Primary Faculty Consultant: Mistrick Technical Assignment #2 Electrical Systems Existing Conditions and Building Load Summary Report Executive Summary The Greenwich Academy Upper School is fed by a 13.2 kv source on the primary winding of a 750 kva transformer. The secondary winding is 208Y/120 V. The system is fed radially from a main distribution panel located in the basement. All electrical panels, as well as most mechanical devices, are located in various rooms on the basement level. There is also a 200 kva generator on-site to provide power in case of emergencies. The purpose of this report is to gather information on the type of electrical systems and loads in the building, and also to compare this data to an NEC-standard design load. The results of this comparison show that the 750 kva transformer is not adequate to provide for the 1134 kva demand of the lighting, receptacle, and mechanical systems. This is potentially due to an overly conservative approach to calculating the design loads. More information is being sought on this topic, and the results will be provided in a forthcoming addendum. Page 1 of 10

2 Matthew Fracassini Lighting/Electrical Greenwich Academy Upper School Greenwich, CT Primary Faculty Consultant: Mistrick Table of Contents Technical Assignment #2 Electrical Systems Existing Conditions and Building Load Summary Report Part I: System Overview...3 (fig 2.1: Single Line Diagram)...3 Part II: Discussion of System Components...4 System Type...4 Transformer Configuration...4 Emergency Power...4 Overcurrent Protection...4 (fig 2.2: Switchboard MDP Detailed SLD and Schedule)...5 (fig 2.3: Switchboard MDP-EM Detailed SLD and Schedule)...6 Motor Load Distribution...6 (fig 2.4: Typical Layout Diagram for Basement Mechanical Rooms)...7 Power Factor Correction...7 Typical Lighting Systems...7 Part III: NEC Building Design Load Calculations...8 (fig 2.5: Lighting System Component Operating Conditions)...8 (fig 2.6: Total Receptacle Load)...8 (fig 2.7: HVAC Equipment Operating Characteristics)...9 (fig 2.8: Hydraulic Elevator Operating Characteristics)...9 Comparison to Transformer and Feeder Selection...10 Part IV: Electric Utility Load Data...10 *To be included in Addendum B Page 2 of 10

3 Matthew Fracassini Lighting/Electrical Greenwich Academy Upper School Greenwich, CT Primary Faculty Consultant: Mistrick Technical Assignment #2 Electrical Systems Existing Conditions and Building Load Summary Report Part I: System Overview Power is supplied to the Upper School by an existing 13.2 kv connection located on the exterior of the adjacent building, Ruth West Campbell Hall. The existing feeder and 300 kva transformer for the Gymnasium building were used during construction, but were removed after completion of the new conduit duct bank and new transformer. The transformer is located in a vault beneath the exterior stairway closest to the Gym Building. The 750 KVA unit steps the voltage down to 280/120 V. A 4 conduit bank consisting of three (3) #2 (15kV rated) cables feeds the 3000 A Main Distribution Panel (MDP) located in the basement. This switchboard provides 3-phase power to all of the panels in the building (see figure 2.2 for details). (fig 2.1: Single Line Diagram) High Voltage Source Page 3 of 10

4 Part II: Discussion of System Components System Type This arrangement would be considered a radial power distribution system. The single transformer feeds into only one distribution panel. Furthermore, this panel is responsible for all loads in the building. Transformer Configuration Location Rating Type Secondary Winding Phase Transformer Vault 750 KVA Copper Coil 208/120V, 4W 3 Emergency Power A 200 kw Generator, located in the same vault as the transformer, provides 3-phase power at 208/120 Volts. The generator is connected by 2 sets of 4 500MCM THHN conductors to an 800 A Automatic Transfer Switch in order to ensure safe shifting of the loads in the event of a power fault. The emergency switchboard supplies the emergency lighting system and emergency receptacles, as well as the hydraulic elevator with 208/120 V power. (For further details, see figure 2.3) Additionally, in order to ensure safe egress from the building and site. Fortunately, the close proximity of the Middle School and Gymnasium Building should aid the emergency site lighting of the Upper School in keeping the sidewalks and streets well lit. Overcurrent Protection The overcurrent protection devices are all located on the Main Distribution Panel (MDP) or the emergency distribution panel (MDP-EM) in the Electrical Room. At this switchboard, all of the panels are protected from overload and ground faults by 3-pole circuit breakers, with ratings of 60,200, 400, 600, and 800 A. Also used at the same location, but to protect from high-level short-circuits, are fused disconnect switches with ratings of 60, 150, 200, 300, 350, 400, 600, and 800 A. The devices for the MDP-EM are organized in the same way as the MDP, and feature similar breaker and fuse ratings. This panel, like the MDP, is itself protected by a 3000 A 3-pole breaker and 2500A fused disconnect switch. Additionally, a shunt trip circuit break is provided for the hydraulic elevator motor controller. This 3-pole, 100 A breaker is located in the Elevator Mechanical Room. Disconnect switches are located at each MCC in the basement Mechanical Room. Page 4 of 10

5 (fig 2.2: Switchboard MDP Detailed SLD and Schedule) Panel Name Voltage Switch/Fuse Feeder Size Load Type MDP 208/120v 3000A / 2500A (2) 4-500MCM + #3 GND in 3-1/2 C MDP-EM 208/120V 800A / 800A (2) 4-350MCM + #3 GND in 3-1/2 C Emergency DP (see fig. 2.3) Chiller #1 (CH-1) 208/120V 400A / 350A 4-500MCM + #3 GND in 3-1/2 C Chiller #1 Chiller #2 (CH-2) 208/120V 400A / 350A 4-500MCM + #3 GND in 3-1/2 C Chiller #2 DP-MER 208/120V 800A / 800A (2) 4-500MCM + #3 GND in 3-1/2 C LP-1A 208/120V 200A / 200A 4-3/0AWG + #6 GND in 2 C MCC Mech. Room Equip. (see fig 2.6) 1 st, 2 nd, and Bsmt Level Lighting LV-1FL 208/120V 200A / 200A 4-3/0AWG + #6 GND in 2 C Receptacles LV-2FL 208/120V 200A / 200A 4-3/0AWG + #6 GND in 2 C Receptacles Dimmer Rack 1 208/120V 200A / 200A 4-3/0AWG + #6 GND in 2 C DMX Dimming System Dimmer Rack 2 208/120V 400A / 300A 4-350MCM + #4 GND in 3 C DMX Dimming System Dimmer Rack 3 208/120V 400A / 300A 4-350MCM + #4 GND in 3 C DMX Dimming System Gym Switchboard 208/120V 600A / 600A (2) 4-500MCM + #3 GND in 4 C Humidifier 1 (H-1) 208/120V 400A / 400A 4-500MCM + #3 GND in 3-1/2 C Humidifier H-1 Humidifier 2 (H-2) 208/120V 60A / 60A 4-#6AWG + #10 GND in 1 C Humidifier H-2 Page 5 of 10

6 (fig 2.3: Switchboard MDP-EM Detailed SLD and Schedule) Panel Name Voltage Switch/Fuse Feeder Size Load Type MDP-EM 208/120V 3000A / 2500A (2) 4-500MCM + #3 GND in 3-1/2 C Elevator 208/120V 200A / 150A 4-3/0AWG + #6 GND in 2 C Hydraulic Elevator DP-EM 208/120V 600A / 600A (2) 4-350MCM + #1 GND in 3-1/2 C Emergency MCC for MER (see fig 2.6) LP-1EM 208/120V 100A / 100A 4-#2AWG + #8 GND in 1-1/4 C Emergency Lighting LP-2EM 208/120V 100A / 100A 4-#2AWG + #8 GND in 1-1/4 C Emergency Lighting Emergency Emergency DMX 208/120V 60A / 60A 4-#6AWG + #10 GND in 1 C Dimmer Rack Dimming System Motor Load Distribution Fig 2.4 shows a partial plan of the basement level, and the placement of the switchgear, panels, MCCs and HVAC equipment. Since the AHUs, chillers, and cooling towers are all located on the same level as the distribution panels, the electrical supply becomes much simpler. In fact, the only HVAC equipment not located on the basement level are the fan coil units, cabinet unit heaters, and several VAV boxes. However, the distribution panels for these units (i.e. DP-EM and DP-MER) are still located in the Chiller Room on the basement level. A more thorough examination of these panels will come in the design load calculation section of the report. (Note: fig 2.6 details the electrical operating characteristics of the mechanical equipment included in panels DP-EM and DP-MER). Page 6 of 10

7 (fig. 2.4: Typical Layout Diagram for Basement Mechanical Rooms) Power Factor Correction There do not seem to be any capacitors installed in the system to correct the power factor. By this, I can assume that components were probably selected for high power factor values, to avoid needing any corrective measures. Typical Lighting Systems Interior All lighting systems in the building operate on 208 V, as supplied by the main transformer. By far, the most common lighting fixture in the school is the 2 x 4 fluorescent troffer. This fixture is used in all classrooms, offices, and labs. The fixtures were chosen for their energy-saving characteristics, and the redundancy makes maintenance and repair much easier. Other types of lights include some incandescent downlights used in the toilet rooms, corridors, and galleries. Exterior There is an extensive LED system employed in the light chambers, in some of the site lighting, and all throughout the roof terraces. For the chambers, the glulam columns and mullions are lined with LED light pipes and fiber optic strips. As with the interior light, these fixtures all operate on 208V, 3-phase power. However, they are not operated off of the same distribution panels. The entire exterior/led system is fed from DMX dimming panels located in the south of MER room in the basement. Note: Extensive Lighting System Operating Characteristics information to follow in Addendum A. Page 7 of 10

8 Part III: NEC Building Design Load Calculations In this section of the report, the building s systems are analyzed for their power consumption characteristics, and compared to the equivalent NEC design load. Including here is documentation of the electrical operating characteristics of all of the lighting systems, transportation systems, and major mechanical equipment. (fig 2.5: Lighting System Component Operating Characteristics) Type of Space Area (ft2) Allowable Power Density (VA/ft2)* Load (kva) Basement MER Room (Utility Space) Basement South Corridor First Floor Classroom/Office 13, First Floor Lab First Floor Atrium (Light Chambers) First Floor Corridor Second Floor Classroom/Office 12, Second Floor Lab Second Floor Atrium (Stair A) Second Floor Corridor Third Floor Atrium Stair B 140(2) Stair C 63(2) Stair D 89(2) Roof and Courtyards 15, Total Lighting Load kva *These values are taken from the 1999 ASHRAE 90.1 tables. (fig 2.6 Total Receptacle Load) Level Panel # Receptacles Total Receptacle Load (kva)(from schedule) Basement LV-1FL st Floor LV-1FL nd Floor LV-2FL rd Floor LV-1FL Total Load (schedule): 128,460 VA NEC Computed Load 1 st 10, % of value Remaining 50% of value (10,000)*(1.0)= 10,000 VA (128,460-10,000)*(0.5)= 59,230 VA Total Computed Load= 69,230 VA = kva Page 8 of 10

9 (fig 2.7:HVAC Equipment Operating Characteristics) Equipment Panel Description Location Voltage Ph HP Full-Load Current* Load (kw) EF-1 DP-EM Exhaust Fan Basement MER EF-2 DP-MER Exhaust Fan Basement MER EF-3 DP-MER Exhaust Fan Basement MER EF-4 DP-MER Exhaust Fan Basement MER EF-5 DP-MER Exhaust Fan Basement MER SE-1 DP-EM Smoke Exhaust Roof B-1 DP-EM Boiler #1 Boiler Room B-2 DP-EM Boiler #2 Boiler Room B-3 DP-EM Boiler #3 Boiler Room HWP-1 DP-EM Hot Water Pump Boiler Room HWP-2 DP-EM Hot Water Pump Boiler Room GHWP-1 DP-MER Glycol HWP Boiler Room GHWP-2 DP-MER Glycol HWP Boiler Room CH-1 CH-1 Chiller #1 Chiller Room CH-2 CH-2 Chiller #2 Chiller Room CHWP-1 DP-MER Chilled Water Chiller Room Pump CHWP-2 DP-MER Chilled Water Chiller Room Pump (Back-Up) CWP-1 DP-MER Cond. Water Pump Chiller Room CWP-2 DP-MER Cond. Water Pump Chiller Room (Back-Up) CT-1 DP-MER Cooling Tower #1 Exterior CT-2 DP-MER Cooling Tower #2 Exterior GP-1 DP-EM Make-Up Pump Chiller Room DP-EM Irrigation Pump #1 Roof DP-MER Irrigation Pump #2 Roof AHU-1 DP-EM Air Handling Fan Room Unit #1 AHU-2 DP-EM Air Handling Fan Room Unit #2 AHU-3 DP-EM Air Handling Fan Room Unit #3 H-1 H-1 Humidifier #1 Fan Room H-2 H-2 Humidifier #2 Fan Room FCU-A LV-1FL/2FL Fan Coil Unit 1 st /2 nd Floor FCU-B LV-1FL/2FL Fan Coil Unit 1 st /2 nd Floor FCU-C LV-1FL/2FL Fan Coil Unit 1 st /2 nd Floor FCU-D LV-1FL/2FL Fan Coil Unit 1 st /2 nd Floor FCU-E LV-1FL/2FL Fan Coil Unit 1 st /2 nd Floor FCU-F LV-1FL/2FL Fan Coil Unit 1 st /2 nd Floor Total kw NEC Computed Load kw load / PF = kva load (578.2 kw)/(0.9**)= kva *Full Load Amperes were calculated using NEC Table ** A Power Factor of 0.9 was assumed for the building system. (fig 2.8: Hydraulic Elevator Operating Characteristics) Type Model # Voltage Phase Full Load Current Load (kw) Holeless Hydraulic Otis LVM A* 72.1 *At the time of the report, there was no information available on the characteristics of the elevator controller. This figure is the breaker rating from the distribution panel. Therefore, the current is likely overestimated. Page 9 of 10

10 Comparison to Transformer and Feeder Size Based on the calculated loads for lighting, receptacles, HVAC, and transportation, we can now determine the design capacity for the building, size the transformer and feeder, and then compare these to the selected elements. Load Type Load kva Lighting Receptacle HVAC Equipment Elevator 72.1 TOTAL LOAD TOTAL DESIGN LOAD kva The primary, and only, transformer in the building has a capacity of 750 kva. This is far below even the non-factored system load. This might indicate that full load conditions are rarely present in every element in the system at the same time. However, this information is difficult to determine without information about the power consumption from the electric company. When this information is acquired, further analysis will be made on the proper sizing of the transformer. We can still compare the feeder sizes, as they should still be able to handle the additional power demand. Panel Load (A) Feeder Size Capacity OK? MDP 3000* (2) 4-500MCM 854 yes** MDP-EM 800* (2) 4-500MCM 854 yes CH MCM 427 yes CH MCM 427 yes Elevator 200* 4-#3/0 228 yes *These are rated values for the circuit, and are likely overestimated. **This discrepancy is likely due to the fault capacity of the main switchboard. Part IV: Electric Utility Load Data This section of the report will be completed following reception of the necessary utility information from the MEP engineer on the project. This will be included in Addendum B to the main report. Page 10 of 10