The 2016-2017 Auxiliary Electric Team: Justin Griffin Protective Relaying Overcurrent and Differential Relaying Lighting Ethan Wilcox Substation Arrangement and Location Neutral Grounding Methods Equipment Location Dinh Pham UPS/Inverters Battery Sizing Black Start Generator Douglas Heller Lightning Protection Load List One Line Natnael Hailemichael Power Transformers (MAT/RAT/GSU) Instrument Transformers (CT/PT) Phasing Mekebeb Geremew PUS Bus Duct MV Bus Transfer Schemes Rafael Alvarez Motor Control Center Motors Variable Frequency/Speed Drives Mariana Da Silva Bozan SUS Electrical Installation, Conductors, Wiring Three Line Diagram

Power Transformers Instrument Transformers Phasing of the Electric System Natnael Hailemichael

Transformer Sizes and Their %Z Decisions we have made: Two MATs and two RATs (same size RAT and MAT) Both MATs running with fans on (ONAN/ONAF/ONAF) GSU output increased from 275MVA to 290MVA Minimum impedance for fault study Maximum impedance for voltage regulation All SUS transformers have 2.5MVA and 5% impedance rating

Power Transformer Protection Devices that indicate the status of the physical quantities of the transformer Buchholz Relay Oil Level Indicator Devices measuring electrical quantities affecting the transformer Over Current Relay Ground Fault Relay Lightning Arrestor Fire Protection Reinforced concrete for walls, roof, and floor Fire resistance rating of 3hrs Deluge system to sprinkle water during fire

Current Transformers Two types of current transformers C type: ratio error can be determined by calculation from the excitation curve T type: Ratio error must be determined by test due to significant leakage flux We will be using the “C type” current transformers in our design Sizing our CTs (SUS level): Based on the 6.9KV switchgear, we choose a CT rating of C250 CT ratio: S = 2.5MVA, V = 6.9KV, Solve for current I = 209A. We want the ammeter needle to be at 3/5 of the way at full load so CT ratio = 209:3 Actual CT ratio = 350:5 so we choose 400:5 as our CT ratio

Current Transformers 400 : 5 CT rating For metering, you want to be on the linear level For relaying, you can be above the knee point.

Questions? Natnael Hailemichael

Bus-Duct Primary Unit Substation MV Bus Transfer Schemes Mekebeb Geremew

Isolated Phase Bus-Duct The momentary current is depends on what equipment it’s connected to. Ratings (Current ratings based upon 40oC ambient) Rating voltage 18 kV rms Basic impulse insulation level 150kV Rated continuous current 12KA. Momentary current 156 kA Standards and Codes: American National Standards Institute (ANSI IEEE-C37.23) National Electric Code (NEC) (NFPA No. 70)

Cable Bus Cable Bus and Bus Bar systems have similar properties Voltage Drop, Power Consumption, En- closure Size, System Weight as well as short circuit capacities Advantages of cable bus Reliability Service Life Support Requirements System Maintenance Flexibility Material Cost

PUS Bus rating: Max/Nominal voltage 15/ 6.9 kV rms Basic impulse insulation level 95KV Rated continuous current 1.5KA Max fault current 25KA Breaker rating: Max/Nominal voltage 8.2/6.9KV

PUS Continued MV Starter rating: Max/Nominal voltage 7.2/6.9KV Basic impulse insulation level 95KV Rated continuous current 800A Available momentary current rating is 25KA rms symmetrical Standards: IEEE Std C37.20.2™-2015, IEEE Standard for Metal-Clad Switchgear. This standard provides information essential to designing and testing of metal-clad switchgear

MV Bus Transfer Schemes Fast transfer High Speed, Fast transfer. Transient torques are reduced due to speed of transfer. Transfer of complete bus with reduced interruption of process. Avoids parallel transfer operation. Avoids exposure to breaker failure effects. Relevant Standard: ANSI C50.41

Questions? Mekebeb Geremew

Motor Control Center (MCC) Variable Frequency Drives Motors Rafael Alvarez

Motor Control Center A floor-mounted assembly of one or more enclosed vertical sections typically having a horizontal common power bus for the distribution of power and principally containing combination motor-control units. Have both fault capability and overcurrent capability in every bucket NEMA ICS-18-2001, UL 845, NEC, IEEE

Motor Control Center Voltage size: .48 kV Amperage Sizing: Smallest breaker in the MCC that would protect against overcurrent under full load continues conditions Physical limitations More MCC’s mean higher reliability

Variable Frequency Drives and Motors AC induction motors are fixed speed devices because the motors operate from a constant frequency power source VFDs are electronic systems that convert AC to DC and then simulate AC with a changed frequency, thereby changing the speed of the motor Advantage comes from running fans, pumps, or whatever other processes at different speeds Nameplate would tell us if the motor is able to use a VFD on a motor Example: Matching the pump curve with the motor efficiency curve. Increased efficiency equal savings in operating cost

Variable Frequency Drives and Motors Motors started with a VFD will be further away from the time current curve because there is a lower inrush current when the motors are started at a lower speed. The faster a motor is started, the more life that is taken out of it. Starting an induction motor at a lower speed will increase it’s longevity. Higher inrush currents cause heating and stress in the components of a motor. Motor starters, cables, bearings, insulation breakdown More expensive startup cost with a lower maintenance cost. Translates to a lower fixed cost

VFD and Motor Example Pump curve shows the relationship between pressure and flow. As the flow increases the pressure drops. Red line shows needs of the system. The extra flow causes the resistance to increase Without an added device, the system will have a single operating point. This point shows the maximum flow needed at the maximum demand.

VFD and Motor Example VFD pump allows control of the pump’s speed electrically, while using only the energy needed to produce the given flow. Pump would be continuously flowing Results in longer life for the motor as well as a lower operating cost

Questions? Rafael Alvarez

Secondary Unit Substation Electrical Installation Three Line Diagram Mariana Bozan

Secondary Unit Substation 50HP motors and below do not contribute to the fault 𝑀𝑉𝐴 𝑓𝑎𝑢𝑙𝑡 = 3 𝑥𝐿𝑅𝐴 𝐾𝐴 𝑥 𝑉(𝐾𝑉) 𝑋" 𝑑 or 𝑀𝑉𝐴 𝑓𝑎𝑢𝑙𝑡 = 𝑀𝑉𝐴 𝑟𝑎𝑡𝑒𝑑 𝑍 𝑝𝑢 MVA method: Series : 𝑀𝑉𝐴 1,2 = 𝑀𝑉𝐴 1 𝑥 𝑀𝑉𝐴 2 𝑀𝑉𝐴 1 + 𝑀𝑉𝐴 2 Parallel : 𝑀𝑉𝐴 1,2 = 𝑀𝑉𝐴 1 + 𝑀𝑉𝐴 2

Secondary Unit Substation Fault Contribution at SUS bus: 21𝐴|2.23 𝑀𝑉𝐴 NO 21𝐵|3.39 𝑀𝑉𝐴 22𝐴|2.91 𝑀𝑉𝐴 NO 22𝐵|1.43 𝑀𝑉𝐴 23𝐴|0 𝑀𝑉𝐴 NO 23𝐵|1.42 𝑀𝑉𝐴 24𝐴|2.43 𝑀𝑉𝐴 NO 24𝐵|1.25 𝑀𝑉𝐴 25𝐴|2.41 𝑀𝑉𝐴 NO 25𝐵|2.41 𝑀𝑉𝐴

Secondary Unit Substation Fault Contribution of SUS at PUS level ( Considering 2.5 MVA transformers with 𝑋" 𝑑 =5%): 21𝐴|2.13 𝑀𝑉𝐴 21𝐵|3.17 𝑀𝑉𝐴 22𝐴|2.75 𝑀𝑉𝐴 22𝐵|1.4 𝑀𝑉𝐴 23𝐴|0 𝑀𝑉𝐴 23𝐵|1.4 𝑀𝑉𝐴 24𝐴|2.32 𝑀𝑉𝐴 24𝐵|1.22 𝑀𝑉𝐴 25𝐴|2.3 𝑀𝑉𝐴 25𝐵|2.3 𝑀𝑉𝐴 Total contribution of MCC`s and SUS to PUS (not considering MV motors): Total on PUS 21A = 9.5MVA Total on PUS 21B = 9.49 + 1.21 (Fire Pumps MCC) = 10.7MVA

Electrical Installation

Electrical Installation Factors such as temperature, number of conductors, insulation will affect the ampacity of the cable.

Three Line Diagrams

Three Line Diagrams Source : Electroswitch website

Three Line Diagrams

Three Line Diagrams

Questions? Mariana Bozan

Protective Relaying Overcurrent and Differential Relaying Lighting Justin Griffin

MAT Differential Relay CT secondary connection should be opposite of primary. To compensate for the 30 degree shift in a delta- wye transformer. Source : Power System Analysis & Design (5th Edition)

MAT Differential Relay-Cont. Find primary and secondary Currents for transformer. Find secondary current for CTs (primary and secondary) Choose Appropriate CT ratio Choose Tap ratio Keep percent mismatch below 10%

Lighting :Zonal Cavity Ratio Method Takes into consideration the effect that inter-reflectance has on the level of illuminance. Factors to consider Area of room. Reflectance percentage off ceiling, work plane, and floor. Height of lamps from ceiling. Height of work surface from floor. Amount of lights in room.

Step 1 : Find Cavity Ratios Source : Holophane®

Step 2: Determine Cavity Reflectance For Ceiling and Floor Ρcc : Ceiling Cavity Reflectance Ρfc : Floor Cavity Reflectance Pw : Wall Reflectance Source : Holophane®

Step 3: Find the Coefficient of Utilization (CU) CU final = CU (20% floor) x Multiplier for actual ρfc. Source : Holophane®

Step 4: Compute Average Illuminance Level LLF (Light Loss Factor): The amount of light lost throughout life cycle of the lamp. Source : Holophane®

References Holophane® aesl.hanyang.ac.kr/class/are141/zonal%20cavity%20ratio%20method.pdf ABB-41-347.12C : Type HU & HU-1 Transformer Differential Relays

Questions? Justin Griffin

Neutral Grounding Methods Substation Arrangement Equipment Location Ethan Wilcox

Low Resistance Neutral Grounding Resistors rated for 10 seconds with max temperature increase of 760C 200A to 400A for 6.9kV and above 100A to 400A for 2.4kV to 4.16kV Our PUS level motors and switchgear then require 10 Ohm resistors if rated for 400A (fault study indicates about 230A) 6.9kV / 1.73 = ~4000 V / 400 A = 10 Ohms Relays are configured to trip before the 10 seconds is up

High Resistance Neutral Grounding Used for voltage levels below 2.4kV – so we will use this at 480V SUS/MCC level Must limit to 5A to 10A SUS -> 480 V / 1.73 = 277.45V / 5A = 55.5 Ohm or 10A = 111Ohm

Sample Touch Potential Calculation Source: electrical engineering portal – Jignesh Parmar

Considerations for grounding Grounding of our system is extremely important for protective relaying Limiting current – reduces sensitivity Too much current – reduces selectivity Errors in calculations cost money! Source: IEEE C62

Substation Arrangement / Equipment Location Sources should be as close as possible to their loads Long cable lengths present voltage drop issues NEC 210 says total voltage drop between feeder and source should not exceed 5% Refer to table 9 in NEC for values in voltage drop calculations (V = I*R)

Substation Arrangement / Equipment Location Larger conductor sizes result in higher resistances – more voltage drop Be mindful of NEC 210.19 – minimum ampacity and size should be observed or fault conditions run the risk of vaporizing your wires

Questions? Ethan Wilcox

Battery Sizing Uninterruptible Power Supply Black Start Generator Dinh Pham

Load list

Load Classifications L1- Continuous load Solid State Relays Control Relays Indicating Lamps Emergency Bearing Oil Pump Turning Gear Motor Inverter 75KVA Stack lighting L2 – Momentary load Breaker Tripping Motors Staring L3- Non-continuous load Closing breakers

Battery Sizing A1 = L1 + L2 = 1868A (1min) A2 = L1 = 882 A (35 min) 1868 +(882*35) +(897*24) = 54266A/60 =904AH Battery sizing = 904 AH

Battery Sizing

Starting DC Motor 25 HP 125VDC 80% efficiency = 186A Inrush current = 125VDC/0.1 ohm = 1250A 372A=125VDC/(0.1+X) X = (125VDC/372A) -0.1= 0.236 ohm

Battery Sizing Relevant Standards: IEEE Standard 666 - IEEE Design Guide for Electric Power Service Systems for Generating Stations IEEE Standard 485 - Recommended Practice for Sizing Large Lead Storage Batteries for Generating Stations and Substations

Uninterruptible Power Supply (UPS) * Transformer-based UPS Did not oversize the UPS Load up the inverter as much as possible * *_ Each Charger will have a Polarity Ground Detector Circuit built in

Uninterruptible Power Supply (UPS) Relevant Standard IEEE Standard 944 -IEEE Recommended Practice for the Application and Testing of Uninterruptible Power Supplies for Power Generating Stations

Sizing the Black Start Generator The auxiliary load (30MVA) The percent required for startup is 20% 30 MVA x 0.2 = 6 MVA ( Total load required to start the unit ) 6000 HP x 0.2 = 1200 HP ( Total demand on ID Fan motor) Remove the biggest load (ID fan) to determine the running load Starting ID fan is starting demand Maintain minimum voltage when starting the biggest load

Black Start Generator Relevant Standards: IEEE Standard 1547.4 - Guide for Design, Operation, and Integration of Distributed Resource Island Systems with Electric Power Systems [2] Turner, Steve. Considerations For Generator Protection During Black Start Conditions. 1st ed. IEEE, 2010. Print. Grande-Moran, Carlos. Black Start Studies. 1st ed. Siemens, 2006. Print.

Questions? Dinh Pham

Lightning Protection Load List One Line Douglas Heller

Lightning Protection

Lightning Protection Discussed previously the tools for protection How do we determine the areas in our plant that are at risk of a lightning strike? Lightning strike at Torrens Island Power Station near Adelaide, Australia Anthony James :: scribol.com

Lightning Protection The Rolling Sphere Method Helps determine areas of the plant that are susceptible to lightning strikes A large sphere is rolled over the lightning protection in the plant The radius of the sphere is determined by the characteristics of the lightning and the system it is protecting Any equipment touched by the sphere is at risk of a lightning strike Top right :: http://www.electrical-knowhow.com/2014/05/Rolling-Sphere-Method-for-Lightning-Protection-Design.html All others :: http://geospatial.blogs.com/geospatial/2012/07/designing-lightning-protection-for-substations.html

Lightning Protection The Rolling Sphere Method Sphere radius is based primarily on the stroke current of the lightning bolt Somewhat counterintuitively, protecting for less powerful lightning bolts offers the most protection Less stroke current means a smaller sphere Lightning is a highly probabilistic phenomenon, and the sphere must be calculated based on lightning data in the region of the plant Data available from Vaisala Lightning Detection Network Top :: W H http://s359.photobucket.com/user/waltcolorado/library/ Right :: “Monte Carlo…” Gatta, Geri, Lauria, Maccioni http://www.mdpi.com/1996-1073/9/3/139/htm

Lightning Protection Relevant Standard: IEEE Std 998™-2012 (Revision of IEEE Std 998-1996) IEEE Guide for Direct Lightning Stroke Shielding of Substations

Load List

MCC SUS Load List PUS

One Line

One Line Some Key Features: Two pairs of equally sized two- winding MATs and RATs Fast Transfer capability High reliability/Low overhead Emergency Diesel Local Black Start Generator Senior Design 2017 One Line

Questions? Douglas Heller Senior Design 2017 One Line

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