Building Operator Certification Level I A Partnership of the CUNY Institute for Urban Systems Building Performance Lab, the CUNY School of Professional Studies, and the New York State Energy Research & Development Authority
Building Operator Certification Level I (BOCI) Building Systems: Electrical CUNY School of Professional Studies CUNY Building Performance Lab The BOC Power Basics: Lesson 1
Building Electrical Systems Objectives Understand fundamentals of electricity Know fundamental electrical terminologies Apply basic electrical theory when overseeing electrical maintenance and testing
Agenda Electricity Fundamentals Electrical Circuits & Measurement Building Electrical System
Section 1 Fundamentals Magnetism and Induction Motors and Generators Electrical Terms and Ohm s Law
Electrical Fundamentals Video 1: Electricity and Circuits www.youtube.com/watch?v=d2monvkckx4&feature=relmfu NUCLEUS - ELECTRON ELECTRON ORBIT + PROTON NEUTRON BASIC ATOMIC STRUCTURE ELECTRON FLOW - + CONCEPTUAL VIEW OF A CONDUCTOR WITH APPLIED VOLTAGE
Magnetism Permanent Temporary Electromagnetic Fields _ +
Magnetism & Induction Video 2: Electro-Magnetic Induction www.youtube.com/watch?v=hajiighpeuu
Electrical Induction Video 3: How a Solenoid Works www.ehow.com/video_4951183_solenoid-work_.html A N S S N + G - B
Video 4: Motors & Generators 5c http://www.youtube.com/watch?v=d_atc0iko68&feature=related
AC Cycles and Phases One Cycle of single phase AC shown as a sine wave One Cycle of three phase AC shown as a sine wave 0 90 180 270 360 1 Phase 3 Phase
Electrical Induction Video 5: How Electric Motors Work 5b http://www.youtube.com/watch?v=9tgwjvegvoq
Electrical Induction: Transformers Raise and lower voltages Have primary and secondary coils Provide electrical Isolation
Electrical Terms
Ohm s Law Ohm's Law states that one volt pushes one amp through one ohm of resistance P or W = Power (expressed in watts) I or A = Amperage (expressed in amps) V or E = Voltage (expressed in volts) R = Resistance (expressed in ohms) E = I x R {or V = A x Ohms} P= E x I {or W= V x A} E P I R E I
Electrical Laws & Equations (Amps is) Current = Voltage Resistance Current = 120 Volts = 12 Amps 10 Ohms (Watts is) Power = Voltage x Current Power = 120 Volts x 5 Amps Power = 60 Watts
Power Wheel 2 E R x I I 2 R x I E x P R P E R E R P I 2 I P P x R E I 2 E P
Section 2 Electrical Circuits Measuring Electrical Circuits Electrical Safety Electrical Circuit Protection
Circuits
Open and Closed Circuits L1 PB1 PB2 PB1 on rung 1 is open, the circuit is open, the load is de-energized PB2 on rung 2 is closed, the circuit closed, the load is energized L1 L2 L2 Circuits consist of a voltage source, a pathway made of conductors, and a load or loads An open circuit has a break in it and is deenergized A closed circuit has no break and is energized.
Series Circuit: There is only one pathway for current to flow S1 Switch is controlling all the lights in the circuit The two Push Buttons (PB) are in series with the light L1 PB1 PB2 R L2 When either one is open, what happens?
Parallel Circuits: have at least two pathways for current flow. L1 L2 S1 1 L1 2 L2 3 L3 4 L4 This Parallel circuit has four separate pathways for current flow.
Measuring Electricity Do not work on any electric equipment unless you are trained and qualified to do electrical work. Treat all circuits as if they were live. De-energize any circuit before working on it. Read and learn all safety procedures regarding the meter you use
Measuring Voltage Volt measurements are taken in parallel Voltage drop is voltage used at a load Amperage measurements use clamp-on or line splitter attachments L1 L2 Connect the volt meter in parallel with the component being tested.
Measuring Current - Amps Clamp On Ammeter to measure current
Measuring Volts & Amps OPEN CONTACTS CLOSED CONTACTS V AMPS = 0 VOLTS = 120 AMPS = 10 RESISTANCE = 0 VOLTS = 0 V V CLOSED CONTACTS PITTED & CORRODED AMPS = 10 RESISTANCE = 2.5 OHMS VOLTS = 25
Short Circuits A short circuit has a direct bypass around the load High amperage causes dangerous overheating Circuit protection should open to prevent damage Circuit Protection Fuses contain metal filaments that melt when they reach a specific temperature A circuit breaker opens at a specific temperature caused by a specific amperage
Troubleshooting Fuses A good fuse has continuity nearly zero ohms A blown fuse has no continuity infinite resistance Find the cause of the blown fuse Replace a fuse by putting it into the load side first, then the line side (Note: Never replace a fuse in an energized circuit)
Testing Fuses A good fast acting fuse will register nearly zero resistance A good slow acting fuse will register some resistance A bad, open fuse of either type will register infinite resistance
How Ground Circuits Work Ground wires are part of the safety circuit.
Section 3 Electrical Maintenance Exercise: Testing Transformers Voltage Irregularities
Overheating in Breaker Panels Overloaded circuits are HOT Loose connections are HOT Corroded contacts are HOT Scan all Breaker Panels once a year Exercise Breakers / Switches once a year
No Voltage to a Circuit Check circuit breaker or circuit fuses Find cause of blown fuse or tripped breaker If no breaker is tripped, check power into circuit breaker panel box Reset tripped breaker, replace fuses
Troubleshooting Circuit Breakers A good circuit breaker is in the On position A tripped circuit breaker is in the Middle or Off position Find the cause of the tripped breaker Breakers must be correctly labeled Trace circuits using circuit tracers
Testing a Transformer with Ohmmeter Video 2: How Transformers Work 4 min http://www.youtube.com/watch?v=_mipehrhqro&feature=related "OL"; NO CONTINUITY H1 H2 "OL"; NO CONTINUITY X1 X3 X2 X4 CORRECT, OR GOOD OHM METER MEASUREMENTS Multi-Meter is set to measure Resistance "OL"; NO CONTINUITY
Testing a Transformer with Ohmmeter BAD OHM METER MEASUREMENTS "OL"; NO CONTINUITY H1 H2 X1 X3 X2 X4 "OL"; NO CONTINUITY
Voltage Irregularities Over- and under-voltages Disruptions Voltage surges- high Voltage dips - Low Spikes - High Electric noise Harmonic Voltage Variations Low voltage can cause operational [rpblems Increased amps can increase heat 5% Voltage loss maximum acceptable
Voltage and Phase Monitoring Check for phase loss Check for phase sequence reversal Check voltage quality monitors Maintain cooling equipment for power vault and panel boxes
Section 4 Building Electrical System Electric Safety
Building Electrical System Main Components of System Incoming Service Components Transformer Disconnect Switch Electric Meter Main Distribution Panel Circuit Breaker Panels ( 1 Phase & 3 Phase Power ) Loads in Building (HVAC, Motors, Lighting, etc.
Building Electrical Systems
Building Electrical System Main Distribution Panel Cubicles for each load Disconnect Switch in each cubicle Electric Bus Bar To each Disconnect Disconnect Switches Each to a feeder circuit
Transformers Purpose of Transformers - Raise or lower voltage for use Transformers are used in these locations: - Outside Building: Service to building - Power Vault: Reduce Voltage - Distribution in building - Control Transformers in equipment
Service Transformer / Distribution Transformer Transformer Dry Type Single Phase Step-down: 480/240V or 240/120V Rated Capacity: 15KVA Limited Output: 15,000 Volt-Amps Control Transformer Supplies the control voltage inside the equipment
Building Electrical System FEEDER BRANCH M LARGE MOTORS TO LARGE LOADS BRANCH BRANCH BRANCH CKT MAIN DISTRIBUTION PANEL 480V 120/208V L BRANCH HIGH VOLTAGE PANEL FEEDER LOW VOLTAGE PANEL
Building Electrical System Distribution in the Building Breaker Panel High Voltage 208V / 270V / 480V Three phase or single phase Large Motors Breaker Panel Low Voltage 110V / 120V Single phase only Small loads: lights, plug loads, small equipment
Voltage Phases Single phase low voltage, single phase high voltage, three phase voltage.
Building Electrical System Breaker Panel Low Voltage Lighting Plug Loads Low Voltage Loads
Three Phase Panel PANEL BUS BARS W/WIRE LUGS FOR FEEDER CONNECTION CIRCUIT BREAKERS 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 A B C NEUTRAL CONNECTION BAR GROUND CONNECTION BAR
Circuit Protection A circuit breaker opens at a specific temperature caused by a specific amperage. Fuses contain metal filaments that melt when they reach a specific temperature.
Safety Lock-outs and Tag-outs Work with a partner Let people know where you are working Use lock-outs / tag-outs De-energize circuit Test circuit first Never remove another person s lock or tag
Electrical Standards NEC- National Electrical Code NEMA- National Electrical Manufacturer s Association When to Call for Help ANY TIME YOU WANT TO! If no power into circuit breaker panel box, check fuses protecting the panel box. If fuses are good, call in an electrician Know where in the circuit to stop testing Use test equipment safely
Review and Class Reading Assignments (Weeks 1 and 2) What your reactions? Main learning points you gained from the first class? BOC 107: to review Power Basics (this week, Week 1) http://www1.eere.energy.gov/femp/pdfs/omguide_complete.pdf FEMP Section 9.12 (Ch. 9, Sec. 12, pages 9.135-9.160)