Metering and Energy Information Services (EIS)
What the exam expects
Metering questions cover meter types, interval data, accuracy, and data handling. Know utility revenue meters, submeters, current transformers, potential transformers, pulse outputs, and AMI. A meter multiplier equals the CT ratio times the PT ratio. Demand is usually averaged over a fixed interval, often 15 minutes; a 15-minute kWh reading times four gives average kW. EIS platforms turn interval data into baselines, dashboards, alarms, and M&V inputs. Data quality checks include missing intervals, estimated reads, time synchronization, and unit consistency.
Traps
Forgetting the meter multiplier is a classic error. Another is treating a 15-minute kWh reading as instantaneous kW. Watch CT orientation, reversed phases, and whether the meter reports kWh or kVAh. Do not compare meters with different intervals without conversion.
Worked example
A meter has 400:5 CTs and 2,400:120 PTs. Multiplier = (400/5) x (2,400/120) = 80 x 20 = 1,600. A meter register change of 100 kWh represents 100 x 1,600 = 160,000 kWh. If that energy occurred in a 15-minute interval, average demand is 160,000 x 4 = 640,000 kW, which signals a data or multiplier error, not a real load.