{"id":3513,"date":"2026-10-21T23:53:38","date_gmt":"2026-10-21T15:53:38","guid":{"rendered":"https:\/\/cnbygele.com\/?p=3513"},"modified":"2026-10-21T23:53:40","modified_gmt":"2026-10-21T15:53:40","slug":"power-meter-maximum-demand-interval","status":"publish","type":"post","link":"https:\/\/cnbygele.com\/fr\/blog\/power-meter-maximum-demand-interval\/","title":{"rendered":"Calcul du compteur de demande maximale : intervalles, kW et enregistrements de r\u00e9initialisation"},"content":{"rendered":"

Maximum demand meter calculation usually starts with the energy consumed during a defined interval. Divide that interval’s kWh by its duration in hours to obtain average kW, then identify the largest qualifying interval in the reporting period. For example, 25 kWh consumed in 15 minutes represents 100 kW average demand. This is an illustrative calculation, not a universal billing rule: utilities may use different intervals, apparent-power demand, rolling windows, ratchets or contracted-capacity provisions.<\/p>\n

A factory can consume the same monthly kWh with very different peak demands. The important task is to understand exactly what the meter stores and how its records match the utility’s method. This guide covers interval interpretation and verification, rather than installation diversity calculations or a substitute tariff assessment.<\/p>\n

Distinguish power, energy and recorded demand<\/h2>\n

Power describes the rate of energy use; energy describes the accumulated quantity over time. A meter’s instantaneous kW display, an interval-average kW value and a monthly maximum-demand register therefore represent different observations. They should not be copied into one spreadsheet column without identifying which is which.<\/p>\n

The U.S. Energy Information Administration’s electricity measurement explanation<\/a> provides the power-versus-energy foundation. OpenEnergyMonitor’s energy and power calculation explanation<\/a> also demonstrates converting energy observations into power over time. Neither source establishes the demand interval or tariff applicable to an individual factory.<\/p>\n

Before a comparison, obtain the electricity contract or tariff and the revenue meter’s measurement description. Identify the demand quantity, window length, alignment, reset period and any seasonal restrictions. A plant submeter is useful only when its configuration and location allow a meaningful comparison with the utility record.<\/p>\n

Calculate interval-average kW from energy<\/h2>\n

For a fixed interval lasting t minutes and an active-energy change \u0394E in kWh:<\/p>\n

Average active demand, kW = \u0394E \u00d7 60 \/ t.<\/strong><\/p>\n

For a 15-minute illustrative interval, 25 kWh \u00d7 60 \/ 15 = 100 kW. If the next interval uses 18 kWh, its average is 72 kW. The larger of those two values is 100 kW, but it is the period maximum only if no other qualifying interval has a larger value.<\/p>\n

The formula assumes that the energy difference covers the complete intended interval and that units and multipliers are correct. It does not justify estimating a month’s maximum demand from total monthly kWh. Dividing monthly energy by operating hours produces an average; it can hide short, significant peaks.<\/p>\n

The BY194 multifunction instrument family<\/a> lists maximum-demand measurement. Confirm the ordered model’s demand algorithm, available quantities, interval choices and reset behavior in its manual. Do not assume that the photographed reference instrument displays every function offered across the family.<\/p>\n

\"Disconnected
Product-reference illustration based on the CNBYG BY194 exterior. The meter is disconnected; blank displays and records do not establish installed functions or measured results.<\/figcaption><\/figure>\n<\/p>\n

Understand fixed blocks and rolling windows<\/h2>\n

A fixed-block calculation divides time into non-overlapping intervals. If the blocks are aligned to 00, 15, 30 and 45 minutes, a process burst straddling a boundary contributes energy to two separate averages. The recorded maximum depends on the interval alignment as well as the load.<\/p>\n

A rolling or sliding calculation updates a demand average more frequently using a specified window or subinterval method. A peak that straddles a fixed-block boundary may be captured differently by a rolling method. Identical nominal window lengths do not guarantee identical values.<\/p>\n

Other meter algorithms may emulate a thermal response or use a different prescribed approach. The correct comparison comes from documentation rather than assuming that every field labelled demand is a simple arithmetic block. Record both the integration duration and the update rule.<\/p>\n

If the utility and submeter use different methods, keep their results clearly separated. Reconfigure only under an approved plan that preserves historical settings and makes the effective change date clear. A configuration change can create a break in the trend even when the plant load has not changed.<\/p>\n

Keep kW demand separate from kVA demand<\/h2>\n

Active demand in kW and apparent demand in kVA answer different questions. A low displacement power factor can increase apparent power for a given active load, while distortion can complicate a simple angle-based interpretation. A tariff based on kVA needs the relevant apparent-power measurement or the utility’s specified method.<\/p>\n

Do not divide a monthly maximum kW by an unrelated monthly average power factor and label the result the measured maximum kVA. The values may refer to different times, integration methods and load conditions. A numerical result with the correct unit can still be an invalid comparison.<\/p>\n

For the underlying quantities, see active versus reactive power<\/a>. If demand data is being used to evaluate reactive compensation, use the target power factor guide<\/a> and a properly scoped engineering assessment. Correcting reactive demand does not automatically remove an active-demand peak caused by simultaneous production loads.<\/p>\n

Build a configuration sheet before interpreting a peak<\/h2>\n
\n\n\n\n\n\n\n\n\n\n\n
Record<\/th>\nWhat to capture<\/th>\nInterpretation risk if missing<\/th>\n<\/tr>\n<\/thead>\n
Demand quantity<\/td>\nkW, kVA, current or another documented channel<\/td>\nComparing unlike registers<\/td>\n<\/tr>\n
Window method<\/td>\nFixed block, rolling subinterval or another algorithm<\/td>\nDifferent peaks from the same load history<\/td>\n<\/tr>\n
Time basis<\/td>\nInterval length, alignment, time zone and clock synchronization<\/td>\nPeaks assigned to different production events<\/td>\n<\/tr>\n
Measurement scaling<\/td>\nCT and VT ratios plus primary or secondary basis<\/td>\nConsistent multiplier errors<\/td>\n<\/tr>\n
Reset policy<\/td>\nManual, scheduled, billing-period or power-cycle behavior<\/td>\nLost maxima or mixed reporting periods<\/td>\n<\/tr>\n
Meter location<\/td>\nUtility incomer, transformer feeder or production circuit<\/td>\nTreating one feeder as the whole site’s demand<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n

This table is a project documentation checklist. It specifies no universal demand duration, accuracy tolerance or billing acceptance rule. Obtain those requirements from the actual meter documentation and applicable supply agreement.<\/p>\n

Associate the maximum with a useful timestamp<\/h2>\n

A maximum-demand number without its date and time is difficult to act on. Record the interval start or end convention, time zone and any daylight-saving handling. A timestamp showing the end of a window can be misread as the instant when a motor started, even though the value summarizes the preceding period.<\/p>\n

Match the interval with production records, shift changes, large equipment starts, HVAC operation and onsite generation. Use the timestamp to select a period for investigation, not to infer causation from coincidence. Several moderate loads operating together may explain a peak more accurately than one conspicuous machine.<\/p>\n

Consider missing data and communication outages as well. A meter can retain a maximum while a supervisory system fails to collect the matching interval. Mark that gap rather than filling it with zero. Preserve the original meter record before resetting or replacing equipment.<\/p>\n

The separate power data logger guide<\/a> explains the broader role of time-series recording. For demand analysis, choose an interval and logging arrangement capable of resolving the operational question instead of assuming a monthly total is sufficient.<\/p>\n

Verify calculations against a controlled record<\/h2>\n

Start with a complete, time-aligned sequence of cumulative energy readings or an exported interval-energy file. Confirm that the readings represent the same active-energy direction and that register rollover, resets or replacements have been handled. Convert each energy difference using the documented interval length.<\/p>\n

For a fixed-block meter using the same boundaries, compare the calculated interval values and maximum with the meter’s stored records. Account for display rounding and energy resolution. A discrepancy concentrated near boundaries can indicate clock alignment, while a consistent multiplier can indicate unit or transformer scaling.<\/p>\n

Do not invent a general percentage acceptance band. The project must define the measurement objective, reference method and instrument limitations. Where formal billing accuracy or a dispute is involved, use the applicable metering requirements and authorized verification process.<\/p>\n

For an installation with export, specify how imported and exported active energy are treated. A net-energy interval can conceal substantial flows in both directions. The meter’s demand register may follow a different convention. Read the definitions before interpreting an apparent zero-demand interval.<\/p>\n

\"Disconnected
Product-reference illustration based on the CNBYG BY194 exterior. The meter is disconnected; blank displays and records do not establish installed functions or measured results.<\/figcaption><\/figure>\n<\/p>\n

Turn the result into an operational decision<\/h2>\n

A useful demand review identifies which intervals matter, what loads were active and whether the peak is repeatable. Staggering controllable loads may reduce overlapping demand, but the effect must be tested against the real interval method and production requirements. Avoid promising savings based only on a proposed operating schedule.<\/p>\n

Keep the scope of reactive-power equipment clear. A capacitor bank or SVG can address an appropriate reactive-power requirement; it is not a general replacement for active-load management. If the tariff depends on apparent power, evaluate the coincident electrical conditions rather than quoting a percentage reduction in all demand charges.<\/p>\n

For a meter inquiry, provide the electrical arrangement, CT\/VT details, required demand channels, intended interval method, clock requirements, data export needs and reset permissions. Request written confirmation of the exact model and firmware behavior. That information is more useful than asking only whether a meter has a maximum-demand screen.<\/p>\n

Further learning: power is a rate of energy transfer<\/h2>\n

Khan Academy Physics explains electrical power and its relationship with transferred energy in the following lesson. It supports the distinction behind kW and kWh; it does not define industrial demand algorithms or a utility tariff.<\/p>\n