{"id":3409,"date":"2026-10-16T09:00:00","date_gmt":"2026-10-16T01:00:00","guid":{"rendered":"https:\/\/cnbygele.com\/?p=3409"},"modified":"2026-10-14T19:40:19","modified_gmt":"2026-10-14T11:40:19","slug":"elevator-escalator-drive-harmonics","status":"publish","type":"post","link":"https:\/\/cnbygele.com\/th\/blog\/elevator-escalator-drive-harmonics\/","title":{"rendered":"\u0e2a\u0e31\u0e0d\u0e0d\u0e32\u0e13\u0e23\u0e1a\u0e01\u0e27\u0e19\u0e43\u0e19\u0e23\u0e30\u0e1a\u0e1a\u0e02\u0e31\u0e1a\u0e40\u0e04\u0e25\u0e37\u0e48\u0e2d\u0e19\u0e25\u0e34\u0e1f\u0e15\u0e4c\u0e41\u0e25\u0e30\u0e1a\u0e31\u0e19\u0e44\u0e14\u0e40\u0e25\u0e37\u0e48\u0e2d\u0e19"},"content":{"rendered":"

Elevator drive harmonics are distorted input currents produced by the drive’s power converter, rather than simply by the elevator motor. Their importance depends on converter design, trip load, supply impedance and the combined operation of other loads. Start by measuring the elevator feeder and building supply during representative trips, regeneration and standby. Then distinguish harmonic distortion from voltage dips, control interference and mechanical faults before selecting mitigation. Escalator drives need a similar electrical investigation, but their longer running periods and passenger-dependent loading require a different operating log.<\/p>\n

Identify the converter before choosing a remedy<\/h2>\n

An elevator drive has an input stage, a DC link and a motor-side inverter. Different input arrangements draw different current waveforms. A diode rectifier, a regenerative converter and an actively controlled front end cannot be treated as interchangeable harmonic sources. Obtain the actual drive documentation and options fitted to the installation; a model family name alone does not establish its input circuit.<\/p>\n

List the drive, existing input reactor, supply transformer, generator connection and any installed harmonic filter. Include controller and auxiliary supplies separately. A bank of elevators may share a distribution board while lighting, ventilation or other equipment uses the same upstream transformer. This matters because a correction device installed on one feeder does not automatically address every distortion source at the building connection.<\/p>\n

Modernisation projects deserve particular care. Replacing an older motor or controller can change the electrical load even when the rated elevator capacity remains the same. Preserve the previous single-line drawing as historical evidence, but use the verified current arrangement for calculations and procurement. Do not assume an older filter remains compatible with a new regenerative drive.<\/p>\n

Record trips, regeneration and standby as separate states<\/h2>\n

Elevators operate intermittently. Acceleration, steady travel, deceleration, door operation and waiting can produce different input-current conditions. Record trip direction, passenger or test load, approximate travel distance and which other cars are operating. Use controller information only through an approved access method; harmonic investigation must not bypass interlocks or interfere with service functions.<\/p>\n

Regeneration depends on the drive arrangement and mechanical loading. A regenerative system can return power to the supply in some travel conditions, while a different system may dissipate braking energy elsewhere. Reversed active-power direction is not itself a harmonic fault. Retain the sign of power in the log and obtain the drive manufacturer’s explanation of the converter modes.<\/p>\n

Escalators often run for longer periods, with changing loading and possible speed reduction during light traffic. Log normal running, loaded operation and any approved standby mode. A short unloaded sample cannot establish the thermal or distortion performance of a busy escalator feeder. Conversely, a brief extreme condition should not be presented as the normal operating profile.<\/p>\n

\n\n\n\n\n\n\n\n\n\n\n
Operating condition<\/th>\nEvidence to record<\/th>\nWhat the evidence helps distinguish<\/th>\n<\/tr>\n<\/thead>\n
Elevator acceleration<\/td>\nPhase currents, voltage, trip direction and simultaneous cars<\/td>\nA repeated converter-load pattern versus an upstream voltage dip<\/td>\n<\/tr>\n
Elevator deceleration<\/td>\nActive-power sign, drive mode and harmonic spectrum<\/td>\nRegeneration versus a separate disturbance<\/td>\n<\/tr>\n
Several cars travelling<\/td>\nBuilding feeder current and timestamped individual trip logs<\/td>\nCoincident loading and shared supply distortion<\/td>\n<\/tr>\n
Elevator standby<\/td>\nFundamental current, harmonic amperes and percentage distortion<\/td>\nA large percentage caused by a small denominator<\/td>\n<\/tr>\n
Escalator loaded running<\/td>\nStable current, enclosure temperature observations and passenger-state note<\/td>\nSustained operation versus a short transient<\/td>\n<\/tr>\n
Generator operation<\/td>\nSupply configuration, voltage waveform and permitted load sequence<\/td>\nBehaviour on a different source impedance<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n

This is a qualitative investigation checklist, not a set of compliance limits. Select the actual recording intervals, instrument method and acceptance criteria for the project. Measurement-method guidance includes IEC 61000-4-7<\/a>, while the project power-quality plan should state which quantities and operating conditions will be assessed.<\/p>\n

Measure both the elevator feeder and the supply interface<\/h2>\n

The feeder measurement helps locate the source. The upstream measurement shows how the source interacts with the installation. Establish the intended point of common coupling with the responsible engineer or utility before applying a supply-interface requirement. An internal drive terminal is not automatically that point.<\/p>\n

Use suitable voltage connections and current sensors, with installation by qualified personnel under the site’s electrical-safety procedures. Confirm sensor ratio, orientation, phase association and instrument configuration before trusting the result. Incorrect current-transformer placement can make an apparent filter-performance problem out of a measurement error. The AHF CT placement guide<\/a> addresses this supporting measurement task.<\/p>\n

Record voltage distortion, current spectrum, fundamental current, relevant harmonic amperes and active and reactive power alongside the operating log. Keep instrument location and source configuration in every exported file. If instruments are moved during the survey, identify the change explicitly rather than merging different locations into an unexplained trend.<\/p>\n

For simultaneous instruments, align timestamps and confirm their recording methods are comparable. A missed acceleration interval can make two readings appear contradictory. The wider meter placement guide<\/a> helps define feeder and upstream observation points. If a site has only one suitable analyser, plan repeatable operating tests and explain the uncertainty introduced by non-simultaneous recordings.<\/p>\n

Interpret harmonic amperes before reacting to percentages<\/h2>\n

Current total harmonic distortion, THDi, relates harmonic content to fundamental current. A lightly loaded drive can therefore show a high percentage without carrying the highest harmonic amperes observed during the day. Always retain both quantities. This is especially important when comparing standby and full trips or when several elevators share the same feeder.<\/p>\n

Total demand distortion, TDD, uses a demand-current reference rather than the instantaneous fundamental used in THDi. These quantities serve different comparisons. Do not relabel a THDi reading as TDD or choose a demand reference solely to improve a reported result. Establish the appropriate demand definition and supporting records in the acceptance plan.<\/p>\n

For illustration only, suppose a recorded harmonic RMS total is 4 A and fundamental current is 20 A. Their ratio gives 20% THDi. At another operating state, 1 A of harmonic current and 2 A fundamental current gives 50%. The second percentage is larger, but its harmonic amperes are lower. These invented teaching values are not CNBYG performance data, an elevator specification or a pass\/fail threshold.<\/p>\n

IEEE 519-2022<\/a> addresses harmonic control at the supply interface and distinguishes its steady-state scope from transient events. Apply the relevant project criteria using the correct location and definitions. Do not use one universal current-distortion percentage to approve every drive, feeder and building without considering the applicable conditions.<\/p>\n

Separate harmonics from voltage dips and interference<\/h2>\n

A drive trip does not prove that harmonics caused it. Obtain the fault code, timestamp and service engineer’s findings. A supply voltage dip, phase loss, DC-link issue, control-supply interruption or mechanical problem can have a similar visible outcome. Correlate the event with voltage and current records before selecting a filter.<\/p>\n

Motor-side high-frequency switching and cable-related interference also differ from low-order input-current harmonics. An input harmonic filter is not a general substitute for correct motor-cable practices, shielding, grounding or the drive manufacturer’s EMC instructions. Keep the investigation’s frequency range and measurement method clear. Do not promise to resolve communication or encoder faults merely because an input-current percentage improves.<\/p>\n

When disturbances affect multiple unrelated loads simultaneously, investigate the shared supply. If only one car faults at a particular travel condition, examine its drive and control records alongside the electrical data. Either pattern may require several specialists. Avoid changing elevator safety-related controls as part of an exploratory power-quality test.<\/p>\n

Match mitigation to the measured problem<\/h2>\n

A line reactor may be part of the drive manufacturer’s recommended input arrangement, but its effect depends on the converter and supply. Verify compatibility and operating consequences rather than prescribing a reactor solely from drive power. Existing equipment must be included in the final arrangement so that new components do not duplicate or conflict with it.<\/p>\n

A passive harmonic solution needs engineering review of loading range, supply impedance, capacitor interaction and resonance. A device appropriate at one operating condition may behave differently during standby or generator operation. Document the intended connection point and test the permitted configurations. Ordinary power-factor capacitors do not automatically remove drive harmonics and can introduce an additional interaction that requires assessment.<\/p>\n

An active harmonic filter can be considered where the measured harmonic-current profile and network conditions support it. Size from the correction task across representative operation, allowing for the functions, derating and response verified for the selected model. Motor rated current alone is not the required correction current. The CNBYG AHF product page<\/a> provides the product connection for an enquiry; confirm detailed capability and project suitability with engineering documentation.<\/p>\n

\"Harmonics
Product-reference illustration of the CNBYG AHF exterior. Equipment is disconnected; no wiring, installation or measured performance is claimed. Label text is simplified for illustration; use actual equipment safety labels and instructions.<\/figcaption><\/figure>\n<\/p>\n

The reference illustration shows the disconnected product exterior for enclosure and installation discussion. It does not demonstrate an approved elevator connection, measured harmonic reduction or suitability for a particular drive. A site-specific drawing and equipment documentation are required before installation.<\/p>\n

Plan an acceptance test that can be repeated<\/h2>\n

Agree the test states before installation: representative trips, permitted simultaneous operation, regenerative conditions, escalator loading and any authorised generator configuration. Preserve the same measurement positions and instrument settings between baseline and final testing. Include enough operating information to show whether the comparison is fair.<\/p>\n

Compare harmonic amperes and the relevant distortion quantities with voltage behaviour and operating performance. A lower percentage during a different load state is not a reliable before-and-after improvement. Record correction-device status, alarms and relevant environmental conditions. If the filter is unavailable during one test, label that interval clearly.<\/p>\n

Check normal service functions with the elevator service organisation after electrical changes. Harmonic acceptance does not replace statutory inspection, functional safety or drive commissioning. Any unexpected behaviour should trigger a controlled review, rather than repeated adjustment of compensation settings without a documented reason.<\/p>\n

The AHF performance verification guide<\/a> supports the electrical comparison. For buildings containing several interacting load types, the shopping mall power-quality guide<\/a> provides the wider distribution-system context without replacing the elevator-specific operating log.<\/p>\n

\"Harmonics
Product-reference illustration of the CNBYG AHF exterior. Equipment is disconnected; no wiring, installation or measured performance is claimed. Label text is simplified for illustration; use actual equipment safety labels and instructions.<\/figcaption><\/figure>\n<\/p>\n

Prepare a useful enquiry package<\/h2>\n

Send the actual input-converter details, drive quantity, supply voltage, transformer information, verified single-line drawing and existing correction equipment. Add measurement files with their locations, demand basis, representative operating states and fault timestamps. Separate measured facts from suspected causes so that the proposed equipment solves the documented problem.<\/p>\n

Include available mounting space, enclosure conditions, access restrictions, shutdown windows and coordination responsibilities. Ask the supplier to state the proposed connection point, sensor arrangement, correction functions, operating limits and acceptance method. Obtain model-specific information instead of relying on a generic image or a claim that any filter suits any drive.<\/p>\n

If the survey has not captured a critical state, identify the missing evidence and plan the additional measurement. An honest incomplete survey is more useful than a specification built on guessed harmonic current. The final deliverable should let another engineer reproduce the measurement and understand why the chosen remedy was considered.<\/p>\n

Further learning: harmonic-current fundamentals<\/h2>\n

The following NPTEL IIT Delhi lecture, Power Quality: Standards and Monitoring, supports the measurement and acceptance discussion. It provides general power-quality education rather than an elevator installation tutorial or a product endorsement.<\/p>\n