Transformer Oil Testing Explained
Breakdown voltage, moisture, acidity and dissolved gas analysis: what each oil test measures, what the results mean, and when to act before a failure.
Guides for Field Engineers
Practical, field-written guides on the topics working engineers actually meet on site. No catalogue copy, no invented specifications — just the theory, the procedure and the judgement calls, explained plainly.
Insulation Resistance & PI Test, Step by Step
Setup, safety, connections, readings at 15 seconds, 60 seconds and 10 minutes, temperature correction, and how to interpret polarization index values.
Transformer Vector Groups Explained
What Dyn11, YNd11 and other clock numbers mean, why phase displacement matters, and the four rules for safe parallel operation.
Best Clamp Meters for Electricians
A criteria-based buying guide with no fake reviews: AC/DC, True RMS, jaw size, CAT safety ratings and inrush, plus a checklist to take to the shop.
Transformer Deep: OLTC, Maintenance & Overhauling
OLTC — On-Load Tap Changer Explained
Diverter switch, selector, drive mechanism, tap-change sequence, common faults and operation-count-based maintenance.
Transformer Overhauling, Step by Step
De-energise, drain, open, inspect, repair, dry out, refill, test and controlled energisation — with handover records.
Transformer Maintenance Schedule
Daily, monthly, quarterly and yearly checks, oil sampling intervals, and the records every substation team should keep.
Transformer Oil Processing
Filtration, vacuum degassing and drying, reclamation, and the filter vs reclaim vs replace decision.
Testing & Commissioning, Advanced
SFRA Transformer Testing Explained
What SFRA detects, reading traces by frequency band, and baseline fingerprint comparison.
Tan Delta / Power Factor Test Explained
What dissipation factor measures, guarded test setup, trend interpretation and temperature correction.
Partial Discharge Testing Explained
Sources of PD, electrical, acoustic and UHF detection, phase-resolved patterns and trending.
CT & PT Testing Guide
Ratio, polarity, burden, saturation and knee point — plus the CT open-secondary and PT short-secondary safety rules.
Instrumentation, Control, PLC & SCADA
Instrumentation Transmitters Explained
Pressure, temperature, flow and level transmitters: principles, 4–20 mA loop and HART basics.
Control Valves Explained
Globe, ball and butterfly valves, actuators, positioners, fail-safe action and sizing concepts.
PLC Basics & Ladder Logic
Scan cycle, inputs and outputs, contacts and coils, seal-in circuits, timers, counters and a worked motor example.
SCADA Systems Explained
Field devices, RTU/PLC, Modbus, DNP3 and OPC, HMI design, historian, alarms and OT cybersecurity.
Electronics, Circuits, Arduino, Schematics & PCB
Electronics Circuits Basics
Ohm's law, Kirchhoff's laws, resistors, capacitors and inductors, with worked series, parallel and LED examples.
Arduino Projects for Beginners
Blink, button and sensor projects and low-voltage relay control — safe beginner projects only, never mains.
Reading Electrical Schematics & Simulation
Symbols, single-line and ladder diagrams, and LTspice simulation basics: draw, ground, analyse, verify.
PCB Design with AI
Schematic to Gerber workflow, layout principles, AI-assisted placement and review, KiCad concepts and DFM checks.
Electrical Software: ETAP, AutoCAD Electrical, PLC Advanced
ETAP Basics & Load Flow
Build a one-line diagram, enter equipment data, run a load flow study and read the results.
ETAP Short-Circuit & Protection Coordination
Fault currents, device duties, time-current curves and selective coordination.
ETAP Arc Flash & Motor Starting
Incident energy, boundaries and labels, motor acceleration and voltage dip analysis.
AutoCAD Electrical Basics
Interface, project setup, wires, components and a first motor-starter schematic.
AutoCAD Electrical Schematics & Panels
Multi-wire schematics, panel layouts, terminal strips and project-wide wire numbering.
AutoCAD Electrical Reports & Automation
BOM and wire reports, self-updating title blocks, PLC I/O drawings and templates.
PLC Ladder Logic, Advanced
Timers, counters, sequencers, shift registers and subroutines, with a batching worked example.
PLC Analog, PID & Troubleshooting
4–20 mA scaling, PID control in ladder logic, and a field-to-program-to-field troubleshooting method.
Transformer Protection, Cooling & Construction
Buchholz Relay Explained
Two-float alarm and trip stages, pipe inclination, what relay gas means, and testing — plus how Buchholz fits with differential protection.
Transformer Cooling Systems
ONAN, ONAF, OFAF and OFWF decoded: radiators, fans, pumps, staged cooling control and troubleshooting rising temperatures.
Transformer Protection Explained
Differential with inrush restraint, restricted earth fault, overcurrent backup, Buchholz, pressure and temperature devices, and coordination.
Transformer Construction & Types
Core and windings, core-form vs shell-form, distribution vs power, oil-filled vs dry-type, and how to read a nameplate on site.
Calibration, DCS, VFDs & PID Control
Transmitter Calibration Guide
As-found vs as-left, bench vs field calibration, the five-point check, and the documentation and interval discipline behind good records.
DCS vs PLC Explained
Where PLCs win, where DCS wins, side-by-side comparison, hybrid architectures and phased migration pitfalls.
Variable Frequency Drives Explained
Rectifier, DC link and inverter stages, V/Hz vs vector control, energy savings, harmonics and motor protection.
PID Control Explained
Proportional, integral and derivative terms, windup and anti-windup, manual tuning, Ziegler-Nichols and diagnosing bad loops.
Start with the pillar guide
New to transformer testing? Start with the power transformer testing and commissioning guide, then work through these guides in any order. For the numbers, use the free transformer calculators, and for instruments, the electrical tools buying guide.