Download Building Electrical System - CUNY Building Performance Lab

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
S
N
+
G -
N
S
B
Video 4: Motors & Generators 5c
http://www.youtube.com/watch?v=d_aTC0iKO68&feature=related
AC Cycles and Phases
1 Phase
One Cycle of three phase
AC shown as a sine wave
360
270
180
90
0
One Cycle of single phase
AC shown as a sine wave
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
R = Resistance
E = I x R {or V = A x Ohms}
(expressed in volts)
(expressed in ohms)
P= E x I {or W= V x A}
E
I
P
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
RxI
2
I
P
Rx R
I
Ex
PxR
I
R
P
P
E
E
I
2
E
R
P
I
2
E
P
Section 2
• Electrical Circuits
• Measuring Electrical Circuits
• Electrical Safety
• Electrical Circuit Protection
Circuits
Open and Closed Circuits
L1
L2
PB1
•
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.
L1
PB2
L2
• 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
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
L2
L1
PB1
PB2
R
 When either one is open,
what happens?
Parallel Circuits:
flow.
have at least two pathways for current
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
CLOSED CONTACTS
OPEN CONTACTS
AMPS = 0
VOLTS = 120
V
V
V
CLOSED CONTACTS
PITTED & CORRODED
AMPS = 10
RESISTANCE = 0
VOLTS = 0
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
"OL"; NO CONTINUITY
Multi-Meter is set to measure Resistance
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
BRANCH
FEEDER
M
LARGE MOTORS
TO LARGE LOADS
BRANCH
BRANCH
BRANCH CKT
L
MAIN DISTRIBUTION PANEL
480V
HIGH VOLTAGE PANEL
FEEDER
LOW VOLTAGE PANEL
120/208V
BRANCH
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
3
5
7
9
11
13
15
17
2
4
6
8
10
12
14
16
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)