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 E1 – Electrical Fundamentals # 4 - Symbols and Wiring Diagrams.

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Presentation on theme: " E1 – Electrical Fundamentals # 4 - Symbols and Wiring Diagrams."— Presentation transcript:

1  E1 – Electrical Fundamentals # 4 - Symbols and Wiring Diagrams

2  © 2005 Refrigeration Training Services - E1#4 Symbols and Wiring Diagrams v1.2 2 Electrical Loads Loads –Consume electricity –Do work Examples: –Motors –Solenoids –Heaters –Lights

3  © 2005 Refrigeration Training Services - E1#4 Symbols and Wiring Diagrams v1.2 3 Motors Common symbols: (Letters tell what motor is represented) COMP EFM IFM CFM OFM COMP COMPressor EFM Evaporator Fan Motor CFM Condenser Fan Motor IFM Indoor Fan Motor OFM Outdoor Fan Motor

4  © 2005 Refrigeration Training Services - E1#4 Symbols and Wiring Diagrams v1.2 4 Solenoid This will cause an action in a relay or valve When current flows through a coil of wire it creates a magnetic field Electrical symbol for a solenoid coil:

5  © 2005 Refrigeration Training Services - E1#4 Symbols and Wiring Diagrams v1.2 5 Solenoid Valve Magnetic coil energized Plunger pulled up Fluid flows Fluid stops Power off Plunger drops Plunger Seat

6  © 2005 Refrigeration Training Services - E1#4 Symbols and Wiring Diagrams v1.2 6 Heaters Convert electrical energy to heat Symbol for resistance heaters: Examples of heaters: – Auxiliary strip heaters – Crankcase heaters

7  © 2005 Refrigeration Training Services - E1#4 Symbols and Wiring Diagrams v1.2 7 Signal Lights Used to show when something is operating, or when there is a problem. Symbol for signal lights: Letter in the center denotes bulb color: R Red B Blue G Green, etc. RB G

8  © 2005 Refrigeration Training Services - E1#4 Symbols and Wiring Diagrams v1.2 8 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”

9  © 2005 Refrigeration Training Services - E1#4 Symbols and Wiring Diagrams v1.2 9 LOAD CONTROL CIRCUIT LINE 1 Power In 4 Power Out Contactor Cutaway 3 Contacts 2 Coil

10  © 2005 Refrigeration Training Services - E1#4 Symbols and Wiring Diagrams v Symbols for Contactors Symbols are shown “de-energized” (no power) with contacts “normally open” Coil Single pole Contact Double pole Triple pole 115v v, 1  v, 3 

11  © 2005 Refrigeration Training Services - E1#4 Symbols and Wiring Diagrams v Visualizing symbols with power on The following slide illustrates what happens when the power is turned on

12  © 2005 Refrigeration Training Services - E1#4 Symbols and Wiring Diagrams v Contactor coil “energized” Contacts close Single pole Double pole Triple pole 115v v, 1  v, 3  CoilContact

13  © 2005 Refrigeration Training Services - E1#4 Symbols and Wiring Diagrams v 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

14  © 2005 Refrigeration Training Services - E1#4 Symbols and Wiring Diagrams v Symbols for RELAYS Coil “de-energized” (no power) Single pole Normally Closed “NC” # 1 NO #2 NC # 1 NC #2 NO #3 NC Normally Open “NO” Double pole Triple pole

15  © 2005 Refrigeration Training Services - E1#4 Symbols and Wiring Diagrams v Visualizing symbols with power on The following slide illustrates what happens when the power is turned on

16  © 2005 Refrigeration Training Services - E1#4 Symbols and Wiring Diagrams v Symbols for RELAYS Coil “energized” (powered up) Single pole Normally Closed “NC” # 1 NO #2 NC # 1 NC #2 NO #3 NC Normally Open “NO” Double pole Triple pole

17  © 2005 Refrigeration Training Services - E1#4 Symbols and Wiring Diagrams v 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

18  © 2005 Refrigeration Training Services - E1#4 Symbols and Wiring Diagrams v Single Throw Switch Symbols Single Pole – Single Throw (SPST) Double Pole – Single Throw (DPST) Switch open Switch closed L2 Switch open Switch closed L1L1

19  © 2005 Refrigeration Training Services - E1#4 Symbols and Wiring Diagrams v Double Throw Switches Each switch position closes a circuit

20  © 2005 Refrigeration Training Services - E1#4 Symbols and Wiring Diagrams v Single Pole - Double Throw (SPDT) Contacts 1 -3 open Contacts 1 -3 closed Contacts 1-2 closed Contacts 1-2 open

21  © 2005 Refrigeration Training Services - E1#4 Symbols and Wiring Diagrams v Double Pole – Double Throw (DPDT) Contacts 1-2 closed Contacts 4-5 closed Contacts 1-3 closed Contacts 4-6 closed

22  © 2005 Refrigeration Training Services - E1#4 Symbols and Wiring Diagrams v Thermostats COOL OFF HEAT ON FAN AUTO B O W Y G R Symbol depicts a bimetal spring which closes and opens the contacts Tstats are usually shown in their “normal” position, which is open

23  © 2005 Refrigeration Training Services - E1#4 Symbols and Wiring Diagrams v 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

24  © 2005 Refrigeration Training Services - E1#4 Symbols and Wiring Diagrams v 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

25  © 2005 Refrigeration Training Services - E1#4 Symbols and Wiring Diagrams v Pressure Controls Symbol depicts a bellows which operates the contacts Pressure safety controls are usually shown in their “normal” position, which is closed

26  © 2005 Refrigeration Training Services - E1#4 Symbols and Wiring Diagrams v Low Pressure Control

27  © 2005 Refrigeration Training Services - E1#4 Symbols and Wiring Diagrams v 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

28  © 2005 Refrigeration Training Services - E1#4 Symbols and Wiring Diagrams v Symbols for Pressure Controls 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 High pressure control

29  © 2005 Refrigeration Training Services - E1#4 Symbols and Wiring Diagrams v Fuses and Overloads Symbols for safety devices, such as fuses and overloads, are usually shown closed

30  © 2005 Refrigeration Training Services - E1#4 Symbols and Wiring Diagrams v Safety Device Symbols Bimetal overload: 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. High heat and high amperage open this overload switch.

31  © 2005 Refrigeration Training Services - E1#4 Symbols and Wiring Diagrams v Introduction to Wiring Diagrams The following slide is a diagram of an attic exhaust fan –The fan is controlled by a standard switch

32  © 2005 Refrigeration Training Services - E1#4 Symbols and Wiring Diagrams v N Switch controls fan FM Attic Exhaust Fan L1L1

33  © 2005 Refrigeration Training Services - E1#4 Symbols and Wiring Diagrams v Adding controls to the diagram A thermostat replaces the standard switch This allows the fan to operate automatically, based on attic temperatures

34  © 2005 Refrigeration Training Services - E1#4 Symbols and Wiring Diagrams v L1L1 N Add a Thermostat FM Simple Circuit for Attic Exhaust Fan

35  © 2005 Refrigeration Training Services - E1#4 Symbols and Wiring Diagrams v1.2 35


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