Technical articles
Specialist writing on relays, testing, commissioning and substation automation
A Practical Guide to Communication Protocols in Substations and Industrial Automation
Modbus, DNP3, IEC 60870-5-104, IEC 61850, PRP/HSR and OPC UA compared by use case, strengths and limits, with practical criteria for choosing the right protocol.
Read more →The IEC 61850 Architecture: Data Model, SCL and the MMS, GOOSE and Sampled Values Services
From the data model and logical nodes to SCL files, reporting, GOOSE and SV: a technical overview of IEC 61850 together with testing and commissioning notes.
Read more →Integrating Relays and Substation Equipment with SCADA: Signal Mapping, Gateways and End-to-End Testing
A step-by-step method for connecting relays and meters to SCADA: IO list, gateway configuration, signal mapping, point-to-point testing and acceptance criteria.
Read more →Secondary Injection Testing of Protection Relays: Method, Criteria and Reporting
Secondary injection is the most common way to verify protection relays before energisation. We review the steps, curve formulae, tolerances and safety points.
Read more →Comprehensive Substation Commissioning Checklist Before Energisation
Which checks and tests are required before energising a substation? A staged commissioning checklist from documentation and earthing to phasing, protection and handover.
Read more →Principles of Protection Coordination in Distribution and Industrial Networks
Selectivity, speed, sensitivity and reliability: how to choose pickup, coordination time interval and IEC curves for overcurrent and earth-fault relays.
Read more →Transformer Differential Protection (87T): Principles, Settings and Testing
Dual-slope characteristic, vector-group compensation, harmonic restraint against inrush and over-excitation, and how to test a transformer differential relay.
Read more →Testing Current and Voltage Transformers (CT and VT): Ratio, Polarity, Excitation Curve and Burden
CTs and VTs are the eyes and ears of the relay. A practical review of the required tests, accuracy classes such as 5P20 and PX, knee-point voltage and burden calculation.
Read more →Time Synchronisation in Substation Automation: IRIG-B, NTP, SNTP and PTP
Why does one millisecond matter? A comparison of substation time-sync methods, their accuracy, time-server architecture and how to verify time stamps.
Read more →Testing Medium-Voltage Cables: Insulation Resistance, VLF, Partial Discharge and Tan Delta
Which test suits a new cable and which one an ageing cable? Comparing insulation resistance, VLF, partial discharge, tan delta and sheath tests, and how to run them safely.
Read more →Selecting and Commissioning Variable-Frequency Drives (VFDs) for Energy Saving
Drive selection criteria, constant versus variable torque loads, harmonics and filters, commissioning parameters, and how to calculate energy savings on pumps and fans.
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