 One line and Three line diagrams
 Schematics
 Wiring Diagrams
 Logic ladders
 Ancillary prints
 Pictorial instructions
One line diagram (1)
 One line diagrams will typically show in a simple fashion 
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an over view of the station with simplified protection schemes displayed
Relay types, CT location, Remote tripping, and future breaker positions may also be displayed
Location of disconnect switches and grounding devices may be displayed
Demarcation between two entities may be displayed on one line diagram
Sometimes called Meter‐Relay one line
 Three line diagram (2)
 Three line diagrams show all three phases in three phase 
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applications
More detailed representation of AC current flow from source to bus to CT to end device
Both AC current and AC voltage three phase circuits may be represented
Disconnect switches, transfer buses, and grounding devices may be displayed
Great for proving phasing throughout a three phase system
 ANSI Numbers (3)
 American National Standards Institute
 Developed in the United States in 1918 as a method of standardizing electrical device functions
 Simplified print reading and print development from all trades
 Utility, Railroad, Manufacturing
 Institute of Electrical and Electronics Engineers
 Developed in the United States in 1884 as American Institute of Electrical Engineers
 Mainly focused on standardizing the telegraph industry
 AIEE and IRE (American Radio Engineers) combined in 1957 to create IEEE
 Symbol Legend (4)
 Symbol Legends are used to help identify devices on prints
 Contacts, resistors, capacitors, disconnecting devices
 ANSI/IEEE numbers used on the print may be displayed
 Title Block (4)
 Drawing number, Revision number, Sheet number
 Work order number
 Clear description of print classification
 Engineers name…..but no phone number….
 Print Reference list (5)
 Quickly identify all associated prints
 Contact/Input Use Chart(5)
 Used to quickly determine the intended use of an input or output contact associated with relays that have multiple inputs and outputs
 Communication protocol usage and port set up may also be included
 Contact development schedule (6)
 Identifies contact position in contact multiplying 
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devices in both states, activated (on) and relaxed (off)
Lock out relays
Control handles
Reclose ON/OFF switches
Transfer Trip ON/OFF switches
Supervisory control cut out switches
 Schematics
 Schematics are generally drawn with the following assumptions:
 Control circuits are de‐energized
 Contactors are relaxed
 Devices, such as lock out relays, are reset
 Stored energy has been removed
 Circuit breaker springs are relaxed
 Hydraulic/ Pneumatic energy dissipated
 Insolation medium, SF6 gas or mineral oil has been removed
 Circuit breaker open and de‐energized, Transformer de‐
energized
 Schematics present the electrical operation of the device(s) that are represented on the print
 AC schematic (7)
 Present the electrical operation of AC current and AC voltage of the device(s) represented on the print
 DC schematic (8,9,10)
 Present the electrical operation of DC current and DC voltage of the device (s) represented on the print
 ITS HOW IT WORKS!
 Wiring Diagrams present a wiring method to complete the circuits as designed on the schematic
 Field device (11)
 The field device wiring diagram shows the location of each terminal strip in relation to where it actually exists within the device
 Control house (12)
 The control hose wiring diagram shows connections made from field devices also using nomenclature
 Control Panel (13,14,15)
 The control panel wiring print has point to point style wiring method and also shows general location of panel devices
 Logic Ladder (16,18)
 Logic Ladders are used to explain complicated sequences that are interdependent to complete an operation
 Used in conjunction with a schematic to troubleshoot  Capacitor schemes, Auto sectionalizing/ restoration schemes
 Distributed Automation
 Ancillary Prints (20,21)
 Provide additional details that may make understanding 
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a scheme or circuit easier
Communication devices
Communication connections
IRIG or Clock signal connections
Print index
Panel layout
Substation control house layout
Manufacturer's drawings
 Use of notes
 Always read the notes!
 Use of special conductor size
 Use of special lugs/connections
 Instructions on departmental responsibilities
 Special fusing instructions
 Device location notes
 Communication instructions
 Feeling Gassy
 After energizing the alarm circuits for a new gas breaker, you notice the low gas alarm is in solid….but the breaker is full of gas and the gauge shows normal?
 What prints would help me get to the bottom of this issue?
 Feeling Gassy
 After energizing the alarm circuits for a new gas breaker, you notice the low gas alarm is in solid….but the breaker is full of gas and the gauge shows normal?
 What prints would help me get to the bottom of this issue?
 DC schematic (Control and SCADA)
 Wiring diagram for yard apparatus
 Factory drawings
 What considerations are necessary for this repair?
 I can’t hear what chur sayin
 When commissioning a new line protection relay, you notice that the relay is not indicating a change of state of the reclose ON/OFF switch
 What prints would I need to solve this problem?
 I can’t hear what chur sayin
 When commissioning a new line protection relay, you notice that the relay is not indicating a change of state of the reclose ON/OFF switch
 What prints would I need to solve this problem?
 Contact schedule
 Wiring diagram
 DC schematic
 I/O usage chart
 What are some possible causes of this happening?
 Off Kilter
 Upon energizing a new 12Kv breaker you notice the ammeter reads:
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A phase 110 amps
B phase 118 amps
C phase 140 amps
N 224 amps
 CT ratio 1200:5/240:1
 Phase angle meter reads:
 A phase 0.45 amps @0 degrees
 B phase 0.49 amps @ 240 degrees
 C phase 0.58 amps @ 300 degrees
 N 0.93 amps @ 285 degrees
 Off Kilter continued
 What could possibly be the trouble?
 Quick calculation shows the phase angle readings should be:
 A phase 0.45 amps @ 0 degrees
 B phase 0.49 amps @ 240 degrees
 C phase 0.58 amps @ 120 degrees
 N 0.11 amps @ 6 degrees
 What is the issue?
 Off Kilter continued
 What could possibly be the trouble?
 Quick calculation shows the phase angle readings should be:
 A phase 0.45 amps @ 0 degrees
 B phase 0.49 amps @ 240 degrees
 C phase 0.58 amps @ 120 degrees
 N 0.11 amps @ 6 degrees
 What is the issue?
 C phase current circuit is 180 degrees out of phase, the circuit is rolled somewhere
 Off Kilter continued
 What prints would I need to help me correct this issue?
 What considerations should I have before making this repair?
 Off Kilter continued
 What prints would I need to help me correct this issue?
 AC schematic
 DC schematic
 Wiring diagram (yard apparatus and control panel)
 What considerations should I have before making this repair?