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E1 – Electrical Fundamentals
# 4 - Symbols and Wiring Diagrams
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Electrical Loads Loads Examples: Consume electricity Do work Motors
Solenoids Heaters Lights © 2005 Refrigeration Training Services - E1#4 Symbols and Wiring Diagrams v1.0
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Motors Common symbols: (Letters tell what motor is represented) COMP
EFM IFM COMP EFM IFM COMPressor Evaporator Fan Motor Indoor Fan Motor COMP CFM OFM CFM OFM COMP Condenser Fan Motor Outdoor Fan Motor © 2005 Refrigeration Training Services - E1#4 Symbols and Wiring Diagrams v1.0
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Solenoid When current flows through a coil of wire it creates a magnetic field. This will cause an action in a relay or valve. Electrical symbol for a solenoid coil: © 2005 Refrigeration Training Services - E1#4 Symbols and Wiring Diagrams v1.0
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Magnetic coil energized
Solenoid Valve Magnetic coil energized Plunger pulled up Power off Plunger drops This solenoid valve is in the NC (normally closed) position. The flow of liquid or vapor is stopped. When the magnetic coil is energized the plunger is raised and fluid passes under the disk and through the pipe in the direction of the arrow stamped on the side of the valve. Fluid flows Plunger Fluid stops Seat © 2005 Refrigeration Training Services - E1#4 Symbols and Wiring Diagrams v1.0
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Heaters Convert electrical energy to heat
Symbol for resistance heaters: Examples of heaters: Auxiliary strip heaters Crankcase heaters © 2005 Refrigeration Training Services - E1#4 Symbols and Wiring Diagrams v1.0
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R B G Signal Lights R Red B Blue G Green, etc.
Used to show when something is operating, or when there is a problem. Symbol for signal lights: R B G Letter in the center denotes bulb color: R Red B Blue G Green, etc. © 2005 Refrigeration Training Services - E1#4 Symbols and Wiring Diagrams v1.0
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Contactor It is a mechanical switch, operated by a magnetic coil
Energizing the coil closes the contacts Power flows through the contacts to the load For more on contactors: See Topic E2 Subject 3 “Contactors and Motor Starters” © 2005 Refrigeration Training Services - E1#4 Symbols and Wiring Diagrams v1.0
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Contactor Cutaway LINE 1 Power In CONTROL CIRCUIT 2 Coil 3 Contacts
LOAD CONTROL CIRCUIT LINE 1 Power In 2 Coil 3 Contacts 4 Power Out © 2005 Refrigeration Training Services - E1#4 Symbols and Wiring Diagrams v1.0
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Symbols for Contactors
Coil Contact Single pole Double pole Triple pole 115v , 1 , 3 Symbols are shown “de-energized” (no power) with contacts “normally open”. © 2005 Refrigeration Training Services - E1#4 Symbols and Wiring Diagrams v1.0
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Visualizing symbols with power on
The following slide illustrates what happens when the power is turned on. © 2005 Refrigeration Training Services - E1#4 Symbols and Wiring Diagrams v1.0
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Contactor coil “energized”
Contacts close Coil Contact Single pole Double pole Triple pole 115v , 1 , 3 © 2005 Refrigeration Training Services - E1#4 Symbols and Wiring Diagrams v1.0
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Relays Similar to contactors Usually under 20 amp capacity
Contacts may be: Normally open (NO) Normally closed (NC) Or a combination of NO and NC © 2005 Refrigeration Training Services - E1#4 Symbols and Wiring Diagrams v1.0
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Coil “de-energized” (no power)
Symbols for RELAYS Coil “de-energized” (no power) Normally Open “NO” 1 2 Single pole Double pole Triple pole #1 NO #2 NC #1 NC #2 NO #3 NC Normally Closed “NC” © 2005 Refrigeration Training Services - E1#4 Symbols and Wiring Diagrams v1.0
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Visualizing symbols with power on
The following slide illustrates what happens when the power is turned on. © 2005 Refrigeration Training Services - E1#4 Symbols and Wiring Diagrams v1.0
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Coil “energized” (powered up)
Symbols for RELAYS Coil “energized” (powered up) Normally Open “NO” 1 2 Single pole Double pole Triple pole #1 NO #2 NC #1 NC #2 NO #3 NC Normally Closed “NC” © 2005 Refrigeration Training Services - E1#4 Symbols and Wiring Diagrams v1.0
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Introduction to switches
Switches open and close contacts to control a load Contact: the conducting part of a switch Poles: the number of contacts in a switch Throw: the number of closed contact positions per pole. © 2005 Refrigeration Training Services - E1#4 Symbols and Wiring Diagrams v1.0
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Single Throw Switch Symbols
Switch closed Switch open Single Pole – Single Throw (SPST) L1 Switch closed Switch open L2 Double Pole – Single Throw (DPST) © 2005 Refrigeration Training Services - E1#4 Symbols and Wiring Diagrams v1.0
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Double Throw Switches Each switch position closes a circuit
© 2005 Refrigeration Training Services - E1#4 Symbols and Wiring Diagrams v1.0
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Single Pole - Double Throw (DPDT)
Contacts 1-2 closed Contacts 1-2 open 2 1 Contacts 1-3 open Contacts 1-3 closed 3 © 2005 Refrigeration Training Services - E1#4 Symbols and Wiring Diagrams v1.0
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Double Pole – Double Throw (DPDT)
Contacts 1-3 closed Contacts 1-2 closed 2 1 3 5 Contacts 4-5 closed 4 6 Contacts 4-6 closed © 2005 Refrigeration Training Services - E1#4 Symbols and Wiring Diagrams v1.0
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Thermostats COOL OFF HEAT ON FAN AUTO B O W Y G R 70 80 60 50 Symbol depicts a bimetal spring which closes and opens the contacts. Tstats are usually shown in their “normal” position, which is open. © 2005 Refrigeration Training Services - E1#4 Symbols and Wiring Diagrams v1.0
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Symbols for Thermostats
Cooling thermostat In actual operation As the temperature goes up the rise in temperature causes the bimetal to expand the expanded bimetal raises the arm the raised arm closes the contacts © 2005 Refrigeration Training Services - E1#4 Symbols and Wiring Diagrams v1.0
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Symbols for Thermostats
Heating thermostat In actual operation As the room temperature falls the fall in temperature causes the bimetal to contract the contracted bimetal pulls down on the arm the arm closes the contacts © 2005 Refrigeration Training Services - E1#4 Symbols and Wiring Diagrams v1.0
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Pressure Controls Symbol depicts a bellows which operates the contacts. Pressure safety controls are usually shown in their “normal” position, which is closed. © 2005 Refrigeration Training Services - E1#4 Symbols and Wiring Diagrams v1.0
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Low Pressure Control © 2005 Refrigeration Training Services - E1#4 Symbols and Wiring Diagrams v1.0
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Symbols for Pressure Controls
Low pressure control In actual operation As the system pressure falls the fall in pressure causes the bellows to deflate the deflated bellows pulls down on the arm the arm opens the contacts © 2005 Refrigeration Training Services - E1#4 Symbols and Wiring Diagrams v1.0
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Symbols for Pressure Controls
High pressure control In actual operation As the system pressure rises the rise in pressure causes the bellows to inflate the inflated bellows raises the arm the raised arm opens the contacts © 2005 Refrigeration Training Services - E1#4 Symbols and Wiring Diagrams v1.0
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Fuses and Overloads Symbols for safety devices, such as fuses and overloads, are usually shown closed. © 2005 Refrigeration Training Services - E1#4 Symbols and Wiring Diagrams v1.0
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Safety Device Symbols Fuses Overloads Bimetal overload:
High heat and high amperage open this overload switch. Thermal overload relay: Excessive amperage heats the thermal element, which opens the switch. Magnetic overload relay: Excessive amperage creates a magnetic field, which opens the switch. © 2005 Refrigeration Training Services - E1#4 Symbols and Wiring Diagrams v1.0
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Introduction to Wiring Diagrams
Following is a diagram of an attic exhaust fan. The fan is controlled by a standard switch. © 2005 Refrigeration Training Services - E1#4 Symbols and Wiring Diagrams v1.0
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Attic Exhaust Fan FM Switch controls fan L1 N
© 2005 Refrigeration Training Services - E1#4 Symbols and Wiring Diagrams v1.0
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Adding controls to the diagram
A thermostat replaces the standard switch This allows the fan to operate automatically, based on attic temperatures. © 2005 Refrigeration Training Services - E1#4 Symbols and Wiring Diagrams v1.0
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Simple Circuit for Attic Exhaust Fan
Add a Thermostat FM © 2005 Refrigeration Training Services - E1#4 Symbols and Wiring Diagrams v1.0
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Schematic Diagrams The following wiring diagram is a very basic air conditioning unit. The diagram animations show how energizing a relay coil will close a set of contacts. © 2005 Refrigeration Training Services - E1#4 Symbols and Wiring Diagrams v1.0
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A/C Unit with Line Voltage Controls
Compressor runs LEGEND COMP C COMP: Compressor Blower runs BM BR BM: Blower motor C C: Contactor coil Contactor switch TS TS: Thermostat Heat closes Tstat BR BR: Blower relay Blower relay switch © 2005 Refrigeration Training Services - E1#4 Symbols and Wiring Diagrams v1.0
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Schematic Diagrams The following diagram is a little more complex.
A transformer is used to supply power to a low voltage control circuit. © 2005 Refrigeration Training Services - E1#4 Symbols and Wiring Diagrams v1.0
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Air Conditioner Schematic Diagram (Low voltage controls)
LEGEND COMP C C COMP: Compressor CFM: Condenser fan motor CFM IFM: Indoor fan motor C: Contactor IFM IFR: Indoor fan relay IFR CR: Control relay HPS: High pressure switch C CR LPS: Low pressure switch HPS LPS CIT CIT: Comp. Internal tstat Trans: Transformer R: Red tstat terminal CT: Cooling Thermostat The schematic diagram is built step-by-step. Each line, switch, and load is brought in by mouse clicks. Although the instructor has to click many times, it gives complete control over pointing out what is happening as each action is initiated. At the end, students are often amazed by how easy it is to understand a complex diagram when it is built in stages. TRANS Y: Yellow tstat terminal G: Green tstat terminal G Auto On IFR R Y CR CT © 2005 Refrigeration Training Services - E1#4 Symbols and Wiring Diagrams v1.0
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Schematic Diagrams The next slide shows how the low voltage side relates to the high voltage side of the system. © 2005 Refrigeration Training Services - E1#4 Symbols and Wiring Diagrams v1.0
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Air Conditioner Schematic Diagram (Low voltage controls)
LEGEND COMP C C C: Contactor CFM: Condenser fan motor CFM CIT: Comp. Internal tstat COMP: Compressor IFM CR: Control relay CT: Cooling Thermostat IFR HPS: High pressure switch C CR LPS: Low pressure switch HPS LPS CIT IFM: Indoor fan motor IFR: Indoor fan relay Trans: Transformer The schematic diagram is built step-by-step. Each line, switch, and load is brought in by mouse clicks. Although the instructor has to click many times, it gives complete control over pointing out what is happening as each action is initiated. At the end, students are often amazed by how easy it is to understand a complex diagram when it is built in stages. G: Green tstat terminal TRANS R: Red tstat terminal Y: Yellow tstat terminal G On IFR Check out fan circuit Auto Turn Fan “ON” R Y CR CT © 2005 Refrigeration Training Services - E1#4 Symbols and Wiring Diagrams v1.0
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HVACR Industry Standards for Electrical Diagrams
How switch contacts are shown on wiring diagrams: Operating controls are shown in the open position. Example: Thermostats and fan switches Safety controls shown in “normal” position Example: High pressure control (closed) Example: High limit switch (closed) Relay contacts are shown with coil de-energized. Example: Indoor Fan Relay NO contacts (open) Example: Indoor Fan relay NC contacts (closed) © 2005 Refrigeration Training Services - E1#4 Symbols and Wiring Diagrams v1.0
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Schematic Diagram A/C unit with gas heating
Operating controls shown in the “open” position Fan switch (FS) Cooling Tstat (CT) Heating Tstat (HT) Relay switches shown with coil de-energized. Indoor Fan Relay (IFR) coil Normally open contacts Normally closed contacts Safety controls shown in the “normal” position Limit Switch (LS) © 2005 Refrigeration Training Services - E1#4 Symbols and Wiring Diagrams v1.0
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HVACR Industry Standards for Electrical Diagrams
“Detailed Schematic” Numbers on the left are line or circuit numbers Numbers on the right indicate switching information: Which sets of contacts the relay controls (line number) Contact configuration (NO or NC) © 2005 Refrigeration Training Services - E1#4 Symbols and Wiring Diagrams v1.0
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“Detailed” Schematic Diagram
1 2 3 4 5 6 7 9 8 10 Each line is numbered Each line has a load Location of relay’s switch contacts (3, 4) 4 Underlined numbers are normally closed (NC) contacts (1) © 2005 Refrigeration Training Services - E1#4 Symbols and Wiring Diagrams v1.0
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Reading wiring diagrams
Try to visualize what happens when the controls close and power energizes loads The following slide illustrates continuous fan operation © 2005 Refrigeration Training Services - E1#4 Symbols and Wiring Diagrams v1.0
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Continuous Fan Operation
L1 L2 Comp 1 2 3 4 5 6 7 9 8 10 C C 4 - Fan motor will now run continuously on high speed in Off, Heat, or A/C settings CFM IFR High Low 3 - Fan relay contacts change position IFM FS TRANS G On IFR 1 - Switch fan to On (3,4) Auto Cool Y CR 2 - Fan relay coil energized (1) R Off CT W GV LS Heat HT © 2005 Refrigeration Training Services - E1#4 Symbols and Wiring Diagrams v1.0
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Reading wiring diagrams
Which controls, switches, and loads are affected when the A/C is turned on? © 2005 Refrigeration Training Services - E1#4 Symbols and Wiring Diagrams v1.0
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Cooling Mode – Auto Fan Comp 7 - Contactor closes
(Compressor and Condenser Fan start) 1 2 3 4 5 6 7 9 8 10 C C CFM 4 - Fan Relay contacts change position IFR High 5 - Fan motor starts (higher fan speeds are used in A/C) Low IFM FS 6 - A/C contactor coil energized TRANS 3 - Fan relay coil energized G On IFR (3,4) Auto 2 - Room temperature rises Cool Y CR (1) 1 - Switch t-stat to “cool” R Off CT W GV LS Heat HT © 2005 Refrigeration Training Services - E1#4 Symbols and Wiring Diagrams v1.0
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Reading wiring diagrams
Which controls, switches, and loads are affected when the Heat is turned on? © 2005 Refrigeration Training Services - E1#4 Symbols and Wiring Diagrams v1.0
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Heating Mode – Auto Fan Comp Note: Few controls are needed for heating
1 2 3 4 5 6 7 9 8 10 C C CFM IFR High 5 - Fan motor starts on low speed Low IFM 4 - Furnace heat rises, fan switch closes FS TRANS G On IFR 3 - Gas valve opens (3,4) Auto Cool Y CR 2 - Room temperature falls (1) R Off CT 1 - Switch t-stat to heat W GV LS Heat HT © 2005 Refrigeration Training Services - E1#4 Symbols and Wiring Diagrams v1.0
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Four Schematics Show Operation
The following diagrams show these conditions: Evaporator motor operation Condenser motor operation Compressor operation Crankcase heater operation © 2005 Refrigeration Training Services - E1#4 Symbols and Wiring Diagrams v1.0
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Start Indoor Fan Motor (IFM)
L2 C CLB FIELD SCHEMATIC 1 13 23 4 3 L1 POWER CLA 11 21 4 1 COMP L3 SUPPLY 2 Neutral 1 Indoor fan motor STARTS IFC 13 23 3 IFM 11 21 2 Equip end SEPARATE POWER SOURCE OUTDOOR FAN MOTOR REMOTE CFM 1 3 CFR L4 L5 CHR CCH 4 5 C 240v TRAN 24v 1 A C C2 SW OFF FAN L1 1 2 2 C1 IFC C2 C2 C COOL 2 TB1 CHR CFR 1 1 T 3 3 4 CLO OFR CLO LOGIC 5 2 1 CHR CLO C2 IFC Switch fan on LPS HPS 3 C1 C C2 C TRAN 1 CLO IFM contactor energized CHR C2 IFC © 2005 Refrigeration Training Services - E1#4 Symbols and Wiring Diagrams v1.0
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Start Condenser Fan Motor (CFM)
L2 C CLB FIELD SCHEMATIC 2 13 23 4 3 L1 POWER CLA 11 21 4 1 COMP L3 SUPPLY 2 CFM Starts Neutral 1 IFC 13 23 3 IFM 11 21 2 Equip end SEPARATE POWER SOURCE REMOTE CFM 1 3 CFR L4 L5 REMOTE CFM REMOTE CFM CHR CCH 4 5 C 240v OUTDOOR FAN MOTOR TRAN 24v 1 A C C2 SW OFF FAN L1 1 2 C1 IFC C2 C2 C COOL 2 TB1 CHR CT CFR CFR 1 1 3 3 4 CLO OFR CLO LOGIC 5 2 1 CHR CLO C2 IFC Switch to COOL LPS HPS 3 C1 C C2 C TRAN 1 CLO Tstat Closes CFM relay energized CHR C2 IFC © 2005 Refrigeration Training Services - E1#4 Symbols and Wiring Diagrams v1.0
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Start Compressor (Comp)
L2 C CLB FIELD 13 23 4 3 SCHEMATIC L1 Compressor Starts POWER CLA 11 21 4 1 COMP L3 SUPPLY 2 Neutral 3 1 IFC 13 23 3 IFM 11 21 2 Equip end OUTDOOR FAN MOTOR REMOTE CFM 1 3 CFR L4 L5 REMOTE CFM CHR CCH SEPARATE POWER SOURCE 4 5 C 240v TRAN 24v 1 A C C2 SW OFF FAN L1 1 2 C1 IFC C2 C2 C COOL 2 TB1 CHR T CFR CFR 1 1 3 3 4 CLO OFR CLO LOGIC 5 2 1 CHR CLO C2 IFC LPS HPS 3 C1 C C2 C TRAN 1 CLO CHR C2 COMP contactor energized IFC © 2005 Refrigeration Training Services - E1#4 Symbols and Wiring Diagrams v1.0
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Shut off Crankcase Heater (CHR)
L2 C CLB FIELD SCHEMATIC 4 13 23 4 3 L1 POWER CLA 11 21 4 1 COMP L3 SUPPLY 2 Neutral 1 CCH Off IFC 13 23 3 IFM 11 21 2 Equip end REMOTE CFM 1 3 CFR L4 L5 4 5 CHR CCH 240v C TRAN 24v 1 A C C2 SW OFF FAN L1 1 2 C1 IFC C2 C2 C COOL 2 TB1 CHR CFR 1 T 1 3 3 4 CLO OFR CLO LOGIC 5 2 1 CHR CLO C2 IFC LPS HPS 3 C1 C C2 C TRAN 1 CLO CHR CHR relay energized C2 IFC © 2005 Refrigeration Training Services - E1#4 Symbols and Wiring Diagrams v1.0
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Large Air Conditioning System Diagram
Part winding compressors require two contactors 1st contactor pulls in, then 2nd contactor pulls in seconds later Compressor starts easier, less wear Outdoor thermostats control 2nd and 3rd condenser fans © 2005 Refrigeration Training Services - E1#4 Symbols and Wiring Diagrams v1.0
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Commercial A/C remote condensing unit
C: Contactor CB: Circuit breaker CH: Crankcase heater CR: Control Relay DLT: Discharge line tstat FU: Fuse HPS: High pressure switch LPS: Low pressure switch OFC: Outdoor fan contactor OFM: Outdoor fan motor OL: Overload OPS: Oil pressure switch OTS: Outdoor temperature switch TDR: Time delay relay CB1 CB2 COMP COMP COMP CB3 C2 FU 1st Winding energized 2nd Winding energized, Compressor starts OFC1 OFC2 OFC3 OFM1 OFM1 OFM2 OFM2 OFM3 OFM3 Crankcase heater off CR CH C1 C1 Compressor contactor #1 on CR OPS OL1 OL2 LPS HPS DLT TDR TDR Time delay relay starts Time delay contacts close C2 C2 TDR Compressor contactor #2 on OFC1 OFC1 One Outdoor fan starts CR Other Outdoor fans start From building control system OFC2 OFC2 CR CR TS1 Call for cooling OFC3 OFC3 TS2 © 2005 Refrigeration Training Services - E1#4 Symbols and Wiring Diagrams v1.0
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END OF Symbols and Wiring Diagrams
© 2005 Refrigeration Training Services - E1#4 Symbols and Wiring Diagrams v1.0
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