PLC & Controls
Technical knowledge hub
Industrial Electrical Advice & Fault Finding Guides
Practical diagnostic thinking for maintenance and engineering teams dealing with machinery electrical faults, PLC-controlled equipment, motors, drives, sensors and control circuits.
Topics covered
Industrial Fault FindingPLC & ControlsMotors & DrivesSensors & InstrumentationMachine BreakdownsIndustrial MaintenanceControl PanelsElectrical Safety & Testing
Latest guidance
Follow the evidence.
Understand the fault.
These guides explain likely fault groups and responsible diagnostic thinking. They do not replace competent inspection, safe isolation or site-specific testing.
Sensors & Instrumentation
Proximity sensor not detecting — sensor, wiring or PLC fault?
A missing sensor signal can start at the target and mounting, inside the sensor, along its cable, at the PLC input or in the machine sequence.Read technical guide →Control Panels
Why does a contactor keep burning out?
Repeated contactor failure is usually evidence of another electrical, control or load problem. Replacing the same component without finding the cause rarely provides a lasting repair.Read technical guide →Motors & Drives
Three-phase motor humming but not turning — common causes
A humming motor is receiving some electrical energy, but that does not mean it has a healthy three-phase supply or can accelerate its load safely.Read technical guide →Motors & Drives
Contactor pulls in but the motor will not run — what should be checked?
A contactor operating proves only part of the control sequence. The motor circuit, overload, supply, connections and mechanical load still need to be assessed methodically.Read technical guide →PLC & Controls
PLC input is ON but the machine output is not working
An illuminated PLC input confirms one signal has reached the controller. It does not prove the sequence permits the output or that the output circuit and field device are healthy.Read technical guide →Motors & Drives
Common causes of VFD and inverter trips
A VFD trip is a protective response, not a diagnosis. The fault code, operating point, motor, load and supply conditions all help identify why the drive stopped.Read technical guide →Control Panels
24VDC control circuit faults — common causes
A missing or unstable 24VDC control supply can affect many apparently unrelated devices. The circuit should be divided into supply, distribution and load sections before parts are replaced.Read technical guide →Machine or system fault?