Download Technical Means of Automation

Technical Means of Automation
Electricity
Institute of Information Engineering, Automation and Mathematics
September 20, 2016
Electric Charge
attraction
+
–
repulsion
–
–
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Electric Potential and Voltage
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Electric Potential and Voltage
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Electric Potential and Voltage
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Electric Potential and Voltage
ϕ1 = −2V
ϕ2 = +2V
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Electric Potential and Voltage
ϕ1 = −2V
ϕ2 = +2V
Voltage
U = ϕ2 − ϕ1 = 4V
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Electric Potential and Voltage
ϕ1 = −2V
ϕ2 = +2V
Voltage
U = ϕ2 − ϕ1 = 4V
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Electric Potential and Voltage
Current
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Electric Potential and Voltage
E
Current
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Electric Potential and Voltage
ϕ1 = 0V
ϕ2 = 0V
Voltage
U = ϕ2 − ϕ1 = 0V
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Electric Potential and Voltage
Voltage
Current
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Ohm’s Law
I =
U
R
U[V ] - voltage
I [A] - current
R[Ω] - resistance
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Electric Potential and Voltage
ϕ1 = −5V
ϕ2 = 0V
Voltage
U = ϕ2 − ϕ1 = 5V
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Electric Potential and Voltage
ϕ1 = −5V
ϕ2 = 0V
Voltage
U = ϕ2 − ϕ1 = 5V
“Infinitely” large
GROUND
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Electric Potential and Voltage
ϕ1 = −5V
ϕ2 = 0V
Voltage
U = ϕ2 − ϕ1 = 5V
“Infinitely” large
GROUND
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Electric Potential and Voltage
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Sources of Electric Power
1.5V
24V
9V
0-30V
12V
230V
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Current: Flow of Electric Charge
Two notations:
Electron flow (in direction of potential rise)
Conventional flow (in direction of potential drop)
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Current: Flow of Electric Charge
Two notations:
Electron flow (in direction of potential rise) ← TRUE
Conventional flow (in direction of potential drop)
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Current: Flow of Electric Charge
Two notations:
Electron flow (in direction of potential rise) ← TRUE
Conventional flow (in direction of potential drop) ← FALSE
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Current: Flow of Electric Charge
Two notations:
Electron flow (in direction of potential rise) ← TRUE
Conventional flow (in direction of potential drop) ← FALSE
Conventional flow became an international standard.
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Advantages of Conventional Flow Notation
Conventional flow notation:
is a closer analogy to fluid flow in pneumatic, hydraulic, and process flow
systems;
is the standard for modern manufacturers’ documentation (reference
manuals, troubleshooting guides, datasheets, etc.);
is consistent with the “right-hand rule” for vector cross products (which are
essential for understanding electromagnetics at advanced academic levels).
matches all device arrows - no need to “go against the arrow” when tracing
current in a schematic diagram;
makes sense of the descriptive terms sourcing and sinking (transistors, digital
I/O).
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Direct vs. Alternating Current
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Alternating Current
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Measurement of Electric Variables
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Measurement of Electric Variables
voltmeter (voltage)
ammeter (current)
ohmmeter (resistance)
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Measurement of Electric Variables
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Measurement of Electric Variables
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Non-Intrusive Measurement of Current
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Measurement of Electric Variables
Oscilloscope
allows continuous measurement in
real time
voltage and current probes
frequency of sampling (e.g.
100Mhz)
number of channels (2CH, 4CH)
logic signal analyzer (decoding)
built-in features
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Safety
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Risks
power outage
damage to equipment
injury
death
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Mandatory Requirements for Laboratory Exercises
theoretical preparation (will be checked)
NEVER touch any conductor (unless told by instructor)
each electrical connection must be supervised before powered on
students may work only with low-voltage systems (max. 24 V)
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What to Avoid?
any potential situation where a person become a part of electric circuit
providing the equipment with higher voltages than deigned for
shorting circuits
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What to Avoid?
any potential situation where a person become a part of electric circuit
providing the equipment with higher voltages than deigned for
shorting circuits
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Person in Circuit
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What to Avoid?
any potential situation where a person become a part of electric circuit
providing the equipment with higher voltages than deigned for
shorting circuits
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Applying Excessive Voltage
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What to Avoid?
any potential situation where a person become a part of electric circuit
providing the equipment with higher voltages than deigned for
shorting circuits
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Short Circuit
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Short Circuit
Direct interconnection of two differently charged conductors that result into and
excessive electric current.
For example: Connection of primary voltage source directly (without any load) to
ground.
Possible results of short circuit:
circuit damage (parts sensitive to current level)
overheating (melting of conductor)
fire (wire isolation)
explosion
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