AC (Alternating Current)
Power that reverses direction, used in all medium-voltage and utility distribution systems.
Addendum
A pre-award change to bidding or contract documents.
AHJ (Authority Having Jurisdiction)
The regulating body or inspector responsible for enforcing electrical codes and standards (e.g., ESA, local municipality).
ARO (After Receipt of Order)
Timeline indicating that delivery or manufacturing lead time begins only after vendor receives and accepts the PO.
Arc Flash Study
An engineering analysis determining incident energy levels, arc flash boundaries, and required PPE for electrical maintenance.
BIL (Basic Insulation Level)
A transformer and switchgear rating describing the ability to withstand high-voltage surges such as lightning impulses.
Bus Duct / Busway
Prefabricated conductor system used in industrial and commercial power distribution.
BOM (Bill of Materials)
Complete list of materials required for construction or installation.
Cable Tray Systems
Support structures for routing power, control, and communication cables in industrial facilities.
CB (Circuit Breaker)
Protective device used for interruption of fault current.
Change Order (CO)
Formal change to contract price, scope, or schedule initiated after award.
CSA Certification
Canadian safety compliance certification required for electrical distribution equipment.
DGA (Dissolved Gas Analysis)
Diagnostic testing for power transformers to detect insulation breakdown, overheating, and developing faults.
Distribution Transformer
Transforms medium voltage (e.g., 13.8 kV) to utilization voltage (e.g., 600/347V or 480/277V).
Drawing Set
All electrical drawings including single-line diagrams, site plans, cable schedules, and panel schedules.
EPC (Engineering, Procurement, Construction)
A contract structure commonly used in industrial and utility projects.
E-Stop (Emergency Stop)
A safety-rated device designed to immediately cut power to equipment.
FAT (Factory Acceptance Test)
Client-witnessed testing of switchgear, VFDs, MCCs, or transformers at the manufacturer before shipment.
Feeder
Conductors supplying power from distribution equipment to downstream panels or loads.
GIS (Gas-Insulated Switchgear)
Compact MV/HV switchgear using SF₆ or alternative gas for insulation.
Generator Step-Up Transformer (GSU)
Utility transformer that increases voltage from a generator to the grid voltage.
Harmonic Distortion
Voltage or current wave distortion caused by nonlinear loads such as VFDs.
IFC (Issued For Construction)
Final approved drawings used for installation.
IFR (Issued For Review)
Preliminary design documents issued for client or consultant review.
IFP / IFT (Issued for Pricing / Tender)
Documents used for competitive bidding and cost estimation.
Instrument Transformer
Includes CTs (current transformers) and PTs/VTs (potential/voltage transformers) for metering and protection.
LTC (Load Tap Changer)
Transformer mechanism allowing voltage adjustment while energized, used in utility and industrial systems.
LOTO (Lockout/Tagout)
Safety procedure ensuring equipment remains de-energized during service.
MCC (Motor Control Centre)
Assemblies of motor starters, VFDs, and control devices.
MV (Medium Voltage)
Generally 1 kV to 35 kV (varies by region); common in industrial and utility distribution.
NGR (Neutral Grounding Resistor)
Limits fault current in industrial and utility systems.
NEMA Ratings
Enclosure ratings for environmental protection (e.g., NEMA 3R, 4X).
ONAN (Oil-Natural Air-Natural)
Cooling where oil circulates naturally and air convection dissipates heat.
ONAF (Oil-Natural Air-Forced)
Oil circulates naturally, but fans force air across radiators to increase cooling capacity.
OFAF (Oil-Forced Air-Forced)
Oil pumps circulate oil and fans cool the radiators.
ODAF (Oil-Directed Air-Forced)
Oil is forced and directed through specific channels to cool windings more effectively.
ONWF / OFWF (Oil-Natural/Forced Water-Forced)
Transformers cooled by water through heat exchangers.
PO (Purchase Order)
Legal authorization to obtain goods or services.
PPE (Personal Protective Equipment)
Arc-rated protection for electrical work.
Protection Relay
Device used to detect faults and operate breakers or trips.
QA/QC (Quality Assurance / Quality Control)
Framework ensuring installation quality meets utility or industrial standards.
RFI (Request For Information)
Formal request to clarify design ambiguities.
Relay Coordination Study
Engineering analysis to ensure protective devices operate selectively.
SCADA (Supervisory Control and Data Acquisition)
System used by utilities and industrial plants to remotely monitor and control electrical systems.
Single-Line Diagram (SLD)
High-level drawing showing the electrical distribution system.
Substation
Facility with transformers, switchgear, protection systems, and control equipment for utility and industrial power distribution.
Tap Changer
Used to adjust transformer voltage output.
Transformer Impedance (%)
Defines voltage drop and affects fault currents; a key specification in industrial and utility contracts.
TTR (Transformer Turns Ratio) Test
Verifies correct winding ratios.
UPS (Uninterruptible Power Supply)
Backup system providing short-term power for critical loads.
VFD (Variable Frequency Drive)
Controls motor speed; common in industrial fans, pumps, and conveyors.
VT / PT (Voltage or Potential Transformer)
Instrument transformers used for metering or protection.
Warranty Period
Contractual obligation for repairs or replacements after installation.
Witness Testing
Owner- or engineer-attended inspection of equipment tests (FAT or SAT).
Y-Connection (Wye)
Three-phase connection with a neutral point, common in utility distribution.