Voltage, Current & Resistance
Voltage drives current through impedance. Resistance describes opposition to DC current and dissipates heat.
ELECTRICAL & CONTROLS FUNDAMENTALS
Understand the system.
Follow the signal.
Explore how electrical power, sensing and control logic work together in industrial equipment.
Ohm’s Law
For an ohmic element, V = IR. Check temperature and component rating before assuming constant resistance.
Electrical Power
DC power is VI. AC real power also depends on power factor; balanced three-phase power is √3 VI cosφ.
AC vs DC
DC maintains one polarity. AC varies with time; frequency and phase influence inductive and capacitive loads.
Series & Parallel Circuits
Series elements share current. Parallel branches share voltage. Apply Kirchhoff’s laws at loops and junctions.
Single-Phase & Three-Phase
Three-phase systems use phase-displaced waveforms. Distinguish line quantities from phase quantities.
Motors
Electrical energy becomes torque and speed. Starting current, duty, cooling and driven load influence selection.
Relays & Contactors
A control signal operates contacts. Contact ratings and coil voltage must suit the circuit and load.
Fuses & Circuit Protection
Protective devices interrupt abnormal current. Selection depends on circuit characteristics and fault conditions.
Sensors
Sensors turn a physical condition into a signal. Range, accuracy, response time and output type affect suitability.
Limit & Proximity Switches
Limit switches detect mechanical position; proximity sensors detect targets without direct contact.
Solenoids
An energized coil produces motion. Duty rating, heat, supply voltage and return mechanism matter.
Control Circuits
Separate the command path from the power path. Trace the conditions required to energize each output.
Interlocks
Interlocks prevent incompatible operating states. Evaluate loss of power and failed-input behaviour.
PLC Fundamentals
A PLC reads inputs, executes logic and updates outputs. Scan timing affects how events are detected.
Ladder Logic Basics
Contacts represent logical conditions and coils represent outputs. Trace each rung before considering the full sequence.
Electrical Schematics
Read device tags, terminal numbers and cross-references to follow the circuit and its operating sequence.