{"id":2355,"date":"2026-08-09T09:00:00","date_gmt":"2026-08-09T01:00:00","guid":{"rendered":"https:\/\/cnbygele.com\/blog\/airport-terminal-hvac-vfd-harmonics-pcc\/"},"modified":"2026-08-24T17:24:16","modified_gmt":"2026-08-24T09:24:16","slug":"airport-terminal-hvac-vfd-harmonics-pcc","status":"publish","type":"post","link":"https:\/\/cnbygele.com\/vi\/blog\/airport-terminal-hvac-vfd-harmonics-pcc\/","title":{"rendered":"Airport Terminal HVAC VFD Harmonics at the PCC"},"content":{"rendered":"<div class=\"b2b-article\">\n<p style=\"margin:0 0 16px;line-height:1.7\"><strong>Airport terminal HVAC VFD harmonic work should begin with a measurement question, not a device choice.<\/strong> The record needs to state whether it represents one drive lineup, a mechanical-electrical room bus, or the terminal point of common coupling (PCC), and it needs to identify the operating state that produced it. Chillers, air-handling units, pumps, cooling-tower fans, and standby arrangements do not necessarily run in the same combination throughout the day.<\/p>\n<nav class=\"b2b-toc\" style=\"background:#f5f8fa;padding:16px 20px;border-radius:8px;margin:0 0 24px\">\n<h2 id=\"contents\" style=\"margin:42px 0 14px;scroll-margin-top:96px\">M\u1ee5c l\u1ee5c<\/h2>\n<ul style=\"margin:0 0 18px 1.2em;line-height:1.7\">\n<li style=\"margin:0 0 8px\"><a href=\"#part-1-define-the-terminal-question-before-placing-a-meter\">Part 1. Define the terminal question before placing a meter<\/a><\/li>\n<li style=\"margin:0 0 8px\"><a href=\"#part-2-capture-hvac-operating-states-that-change-the-record\">Part 2. Capture HVAC operating states that change the record<\/a><\/li>\n<li style=\"margin:0 0 8px\"><a href=\"#part-3-build-a-pcc-record-that-can-be-compared-responsibly\">Part 3. Build a PCC record that can be compared responsibly<\/a><\/li>\n<li style=\"margin:0 0 8px\"><a href=\"#part-4-separate-harmonic-mitigation-from-other-terminal-power-quality-issues\">Part 4. Separate harmonic mitigation from other terminal power-quality issues<\/a><\/li>\n<li style=\"margin:0 0 8px\"><a href=\"#part-5-review-mitigation-options-against-an-integration-scope\">Part 5. Review mitigation options against an integration scope<\/a><\/li>\n<li style=\"margin:0 0 8px\"><a href=\"#part-6-prepare-a-project-inquiry-without-promising-a-terminal-outcome\">Part 6. Prepare a project inquiry without promising a terminal outcome<\/a><\/li>\n<\/ul>\n<\/nav>\n<h2 style=\"margin:42px 0 14px;scroll-margin-top:96px\" id=\"direct-answer\">Tr\u1ea3 l\u1eddi tr\u1ef1c ti\u1ebfp<\/h2>\n<p style=\"margin:0 0 16px;line-height:1.7\">Airport terminal HVAC VFD harmonic work should begin with a measurement question, not a device choice. The record needs to state whether it represents one drive lineup, a mechanical-electrical room bus, or the terminal point of common coupling (PCC), and it needs to identify the operating state that produced it. Chillers, air-handling units, pumps, cooling-tower fans, and standby arrangements do not necessarily run in the same combination throughout the day.<\/p>\n<p style=\"margin:0 0 16px;line-height:1.7\">An airport terminal is not simply a larger commercial building. HVAC loading can change with passenger flow, ambient conditions, tenant schedules, baggage-area ventilation, and equipment staging. A waveform without that context can describe a moment, but it cannot reliably define a system objective. For broader navigation, start with the <a href=\"https:\/\/cnbygele.com\/vi\/power-quality-system-guides\/\">h\u01b0\u1edbng d\u1eabn h\u1ec7 th\u1ed1ng ch\u1ea5t l\u01b0\u1ee3ng \u0111i\u1ec7n n\u0103ng<\/a>.<\/p>\n<figure style=\"clear:both;display:block;margin:28px 0;float:none;width:100%;\"><img decoding=\"async\" src=\"https:\/\/cnbygele.com\/wp-content\/uploads\/2026\/04\/2.AHF-Active-Harmonic-Filter.webp\" alt=\"AHF enclosure for an airport terminal HVAC harmonic review\" style=\"display:block;max-width:640px;height:auto;float:none;margin:0 auto;\" \/><\/figure>\n<h2 style=\"margin:42px 0 14px;scroll-margin-top:96px\" id=\"part-1-define-the-terminal-question-before-placing-a-meter\">Part 1. Define the terminal question before placing a meter<\/h2>\n<p style=\"margin:0 0 16px;line-height:1.7\">Start by naming the decision the data must support. A record at the input of a variable-frequency drive can help characterize that equipment. A record at a distribution bus can show how multiple HVAC loads interact. A PCC record is used for a broader supply-side question. These are connected observations, but they are not interchangeable.<\/p>\n<p style=\"margin:0 0 16px;line-height:1.7\">For each capture, record the meter position on the one-line diagram, CT ratio and orientation, voltage reference, aggregation interval, capture duration, and the active load group. The result should also state whether emergency or standby equipment was available, running, or isolated. This makes later comparisons reviewable instead of relying on an unlabeled screenshot.<\/p>\n<p style=\"margin:0 0 16px;line-height:1.7\"><strong>Quan tr\u1ecdng:<\/strong> Do not use a drive-terminal reading as proof of terminal-level performance. The PCC boundary, the operating state, and the project acceptance method must be defined together (Source: <a href=\"https:\/\/standards.ieee.org\/ieee\/519\/5892\/\" rel=\"nofollow noopener\" target=\"_blank\">T\u1ed5ng quan v\u1ec1 IEEE 519<\/a>).<\/p>\n<h2 style=\"margin:42px 0 14px;scroll-margin-top:96px\" id=\"part-2-capture-hvac-operating-states-that-change-the-record\">Part 2. Capture HVAC operating states that change the record<\/h2>\n<p style=\"margin:0 0 16px;line-height:1.7\">The most useful airport HVAC log connects each electrical record to a real operating condition. That can include chiller staging, chilled-water pump speed, air-handler demand, cooling-tower fan duty, seasonal mode, and whether a generator or transfer arrangement is part of the observed interval. It is more valuable to capture comparable states than to collect many unrelated snapshots.<\/p>\n<table style=\"width:100%;border-collapse:collapse\">\n<thead>\n<tr>\n<th style=\"border:1px solid #d9e1e8;padding:9px 12px;background:#f5f8fa;text-align:left\">Operating-state question<\/th>\n<th style=\"border:1px solid #d9e1e8;padding:9px 12px;background:#f5f8fa;text-align:left\">What to log<\/th>\n<th style=\"border:1px solid #d9e1e8;padding:9px 12px;background:#f5f8fa;text-align:left\">Why it changes the review<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td style=\"border:1px solid #d9e1e8;padding:9px 12px\">Which HVAC trains were enabled?<\/td>\n<td style=\"border:1px solid #d9e1e8;padding:9px 12px\">Chiller, AHU, pump, and fan identifiers<\/td>\n<td style=\"border:1px solid #d9e1e8;padding:9px 12px\">Different drive groups may share or leave a bus.<\/td>\n<\/tr>\n<tr>\n<td style=\"border:1px solid #d9e1e8;padding:9px 12px\">Was the terminal in a peak, transition, or reduced-load period?<\/td>\n<td style=\"border:1px solid #d9e1e8;padding:9px 12px\">Time stamp, schedule, and demand trend<\/td>\n<td style=\"border:1px solid #d9e1e8;padding:9px 12px\">A peak-load record and a low-load record answer different planning questions.<\/td>\n<\/tr>\n<tr>\n<td style=\"border:1px solid #d9e1e8;padding:9px 12px\">Did equipment stage during the capture?<\/td>\n<td style=\"border:1px solid #d9e1e8;padding:9px 12px\">Start, stop, bypass, and speed-change events<\/td>\n<td style=\"border:1px solid #d9e1e8;padding:9px 12px\">A transient may not represent a steady operating condition.<\/td>\n<\/tr>\n<tr>\n<td style=\"border:1px solid #d9e1e8;padding:9px 12px\">Was standby supply relevant?<\/td>\n<td style=\"border:1px solid #d9e1e8;padding:9px 12px\">Transfer state and source arrangement<\/td>\n<td style=\"border:1px solid #d9e1e8;padding:9px 12px\">The electrical boundary can change with the supply configuration.<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p style=\"margin:0 0 16px;line-height:1.7\">This approach extends the measurement-led logic in the existing <a href=\"https:\/\/cnbygele.com\/vi\/blog\/hvac-vfd-harmonics-commercial-building-pcc\/\">HVAC VFD harmonic measurement guide<\/a>, but keeps the airport terminal operating record distinct from a general commercial-building overview.<\/p>\n<h2 style=\"margin:42px 0 14px;scroll-margin-top:96px\" id=\"part-3-build-a-pcc-record-that-can-be-compared-responsibly\">Part 3. Build a PCC record that can be compared responsibly<\/h2>\n<p style=\"margin:0 0 16px;line-height:1.7\">At the PCC or other agreed system boundary, collect voltage and current information over representative intervals and retain the linked demand record. The goal is not to generate a single universal percentage. The goal is to establish which loading condition, electrical boundary, and measurement settings were present when the record was taken.<\/p>\n<figure style=\"clear:both;display:block;margin:28px 0;float:none;width:100%;\"><img decoding=\"async\" src=\"https:\/\/cnbygele.com\/wp-content\/uploads\/2026\/04\/3.AHF-Active-Harmonic-Filter.webp\" alt=\"Rack-mounted harmonic filter module for HVAC electrical-room planning\" style=\"display:block;max-width:640px;height:auto;float:none;margin:0 auto;\" \/><\/figure>\n<table style=\"width:100%;border-collapse:collapse\">\n<thead>\n<tr>\n<th style=\"border:1px solid #d9e1e8;padding:9px 12px;background:#f5f8fa;text-align:left\">M\u1ee5c so s\u00e1nh<\/th>\n<th style=\"border:1px solid #d9e1e8;padding:9px 12px;background:#f5f8fa;text-align:left\">Gi\u1eef nguy\u00ean ho\u1eb7c ti\u1ebft l\u1ed9<\/th>\n<th style=\"border:1px solid #d9e1e8;padding:9px 12px;background:#f5f8fa;text-align:left\">Decision use<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td style=\"border:1px solid #d9e1e8;padding:9px 12px\">V\u1ecb tr\u00ed \u0111i\u1ec7n<\/td>\n<td style=\"border:1px solid #d9e1e8;padding:9px 12px\">Meter point, CT reference, and voltage source<\/td>\n<td style=\"border:1px solid #d9e1e8;padding:9px 12px\">Prevents a feeder result being compared as a PCC result.<\/td>\n<\/tr>\n<tr>\n<td style=\"border:1px solid #d9e1e8;padding:9px 12px\">C\u01a1 s\u1edf th\u1eddi gian<\/td>\n<td style=\"border:1px solid #d9e1e8;padding:9px 12px\">Kho\u1ea3ng th\u1eddi gian, th\u1eddi l\u01b0\u1ee3ng v\u00e0 tham chi\u1ebfu xung nh\u1ecbp<\/td>\n<td style=\"border:1px solid #d9e1e8;padding:9px 12px\">Connects the electrical data to the operating log.<\/td>\n<\/tr>\n<tr>\n<td style=\"border:1px solid #d9e1e8;padding:9px 12px\">T\u1ea3i c\u1ea5u h\u00ecnh<\/td>\n<td style=\"border:1px solid #d9e1e8;padding:9px 12px\">Running HVAC trains and major coincident loads<\/td>\n<td style=\"border:1px solid #d9e1e8;padding:9px 12px\">Distinguishes system behavior from a single drive event.<\/td>\n<\/tr>\n<tr>\n<td style=\"border:1px solid #d9e1e8;padding:9px 12px\">Ng\u1eef c\u1ea3nh ch\u1ea5p nh\u1eadn<\/td>\n<td style=\"border:1px solid #d9e1e8;padding:9px 12px\">Contractual metric and responsible reviewer<\/td>\n<td style=\"border:1px solid #d9e1e8;padding:9px 12px\">Prevents an article or a generic chart from becoming a compliance verdict.<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p style=\"margin:0 0 16px;line-height:1.7\">The <a href=\"https:\/\/www.energy.gov\/cmei\/ito\/industrial-technologies-office\" rel=\"nofollow noopener\" target=\"_blank\">V\u0103n ph\u00f2ng C\u00f4ng ngh\u1ec7 C\u00f4ng nghi\u1ec7p thu\u1ed9c B\u1ed9 N\u0103ng l\u01b0\u1ee3ng<\/a> provides wider industrial-system context. It does not establish the acceptance limit for a particular terminal installation. Similarly, an IEEE reference provides assessment context, not a shortcut for selecting a capacity from connected motor ratings alone.<\/p>\n<h2 style=\"margin:42px 0 14px;scroll-margin-top:96px\" id=\"part-4-separate-harmonic-mitigation-from-other-terminal-power-quality-issues\">Part 4. Separate harmonic mitigation from other terminal power-quality issues<\/h2>\n<p style=\"margin:0 0 16px;line-height:1.7\">VFD-related questions can overlap with voltage variation, reactive-power demand, switching events, unbalance, grounding, or protection behavior. Treating every electrical symptom as a harmonic-filter question can create an incorrect scope. The investigation should first establish whether harmonic current at the defined boundary is the problem to be solved.<\/p>\n<table style=\"width:100%;border-collapse:collapse\">\n<thead>\n<tr>\n<th style=\"border:1px solid #d9e1e8;padding:9px 12px;background:#f5f8fa;text-align:left\">M\u1ed1i quan t\u00e2m \u0111\u00e3 quan s\u00e1t<\/th>\n<th style=\"border:1px solid #d9e1e8;padding:9px 12px;background:#f5f8fa;text-align:left\">First review question<\/th>\n<th style=\"border:1px solid #d9e1e8;padding:9px 12px;background:#f5f8fa;text-align:left\">\u0110\u1eebng m\u1eb7c \u0111\u1ecbnh<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td style=\"border:1px solid #d9e1e8;padding:9px 12px\">B\u1ea3n ghi d\u00f2ng \u0111i\u1ec7n h\u00e0i<\/td>\n<td style=\"border:1px solid #d9e1e8;padding:9px 12px\">Where was it measured and during which HVAC state?<\/td>\n<td style=\"border:1px solid #d9e1e8;padding:9px 12px\">That one drive is the only source.<\/td>\n<\/tr>\n<tr>\n<td style=\"border:1px solid #d9e1e8;padding:9px 12px\">S\u1ef1 c\u1ed1 \u0111i\u1ec7n<\/td>\n<td style=\"border:1px solid #d9e1e8;padding:9px 12px\">Did the event align with a supply, transfer, or load change?<\/td>\n<td style=\"border:1px solid #d9e1e8;padding:9px 12px\">That a current-mitigation device resolves every voltage event.<\/td>\n<\/tr>\n<tr>\n<td style=\"border:1px solid #d9e1e8;padding:9px 12px\">M\u1ee5c ti\u00eau c\u00f4ng su\u1ea5t ph\u1ea3n kh\u00e1ng<\/td>\n<td style=\"border:1px solid #d9e1e8;padding:9px 12px\">Is dynamic reactive behavior the stated target?<\/td>\n<td style=\"border:1px solid #d9e1e8;padding:9px 12px\">That it has the same selection basis as harmonic-current mitigation.<\/td>\n<\/tr>\n<tr>\n<td style=\"border:1px solid #d9e1e8;padding:9px 12px\">Protection or operational alarm<\/td>\n<td style=\"border:1px solid #d9e1e8;padding:9px 12px\">C\u00f3 m\u1ed1i quan h\u1ec7 \u0111i\u1ec7n n\u00e0o \u0111\u01b0\u1ee3c ghi l\u1ea1i kh\u00f4ng?<\/td>\n<td style=\"border:1px solid #d9e1e8;padding:9px 12px\">That an article can identify the root cause.<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p style=\"margin:0 0 16px;line-height:1.7\">For a related measurement workflow, see <a href=\"https:\/\/cnbygele.com\/vi\/blog\/power-quality-metering-before-apf-svg-rfq\/\">\u0111o l\u01b0\u1eddng ch\u1ea5t l\u01b0\u1ee3ng \u0111i\u1ec7n n\u0103ng tr\u01b0\u1edbc b\u1ed9 l\u1ecdc c\u00f4ng su\u1ea5t t\u00edch c\u1ef1c (APF) ho\u1eb7c m\u00e1y ph\u00e1t t\u0129nh (SVG) RFQ<\/a>. It helps teams frame the evidence needed before a product discussion.<\/p>\n<h2 style=\"margin:42px 0 14px;scroll-margin-top:96px\" id=\"part-5-review-mitigation-options-against-an-integration-scope\">Part 5. Review mitigation options against an integration scope<\/h2>\n<p style=\"margin:0 0 16px;line-height:1.7\">An AHF\/APF review may be appropriate when measured harmonic current is the agreed project objective. It still needs a connection point, CT arrangement, load record, capacity basis, protection review, space, cooling, cable routing, and an acceptance method. The <a href=\"https:\/\/cnbygele.com\/vi\/product\/ahf-active-harmonic-filter-harmonic-control\/\">B\u1ed9 l\u1ecdc s\u00f3ng h\u00e0i t\u00edch c\u1ef1c AHF<\/a> page is a product-line starting point, not a replacement for that engineering scope.<\/p>\n<figure style=\"clear:both;display:block;margin:28px 0;float:none;width:100%;\"><img decoding=\"async\" src=\"https:\/\/cnbygele.com\/wp-content\/uploads\/2026\/04\/4.AHF-Active-Harmonic-Filter.webp\" alt=\"CNBYG AHF enclosure for a defined terminal harmonic-current scope\" style=\"display:block;max-width:640px;height:auto;float:none;margin:0 auto;\" \/><\/figure>\n<p style=\"margin:0 0 16px;line-height:1.7\">Other situations may call for a different review: a reactive-power objective, a network interaction, an upstream event, or a control issue may have a different evidence path. Do not select an option from a generic terminal profile alone.<\/p>\n<h2 style=\"margin:42px 0 14px;scroll-margin-top:96px\" id=\"part-6-prepare-a-project-inquiry-without-promising-a-terminal-outcome\">Part 6. Prepare a project inquiry without promising a terminal outcome<\/h2>\n<p style=\"margin:0 0 16px;line-height:1.7\">An effective terminal-HVAC inquiry describes the electrical boundary and the operating condition, rather than just listing installed motor power. Send the following information with the project question:<\/p>\n<table style=\"width:100%;border-collapse:collapse\">\n<thead>\n<tr>\n<th style=\"border:1px solid #d9e1e8;padding:9px 12px;background:#f5f8fa;text-align:left\">Ng\u01b0\u1eddi mua ph\u1ea3i cung c\u1ea5p<\/th>\n<th style=\"border:1px solid #d9e1e8;padding:9px 12px;background:#f5f8fa;text-align:left\">T\u1ea1i sao \u0111i\u1ec1u \u0111\u00f3 quan tr\u1ecdng<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td style=\"border:1px solid #d9e1e8;padding:9px 12px\">S\u01a1 \u0111\u1ed3 m\u1ed9t s\u1ee3i v\u00e0 c\u00e1c th\u00f4ng s\u1ed1 danh \u0111\u1ecbnh c\u1ee7a h\u1ec7 th\u1ed1ng<\/td>\n<td style=\"border:1px solid #d9e1e8;padding:9px 12px\">Establishes the connection point and supply context.<\/td>\n<\/tr>\n<tr>\n<td style=\"border:1px solid #d9e1e8;padding:9px 12px\">V\u1ecb tr\u00ed \u0111\u1ed3ng h\u1ed3 \u0111o, bi\u1ebfn d\u00f2ng (CT) v\u00e0 \u0111i\u1ec7n \u00e1p chu\u1ea9n<\/td>\n<td style=\"border:1px solid #d9e1e8;padding:9px 12px\">Makes the measurement location unambiguous.<\/td>\n<\/tr>\n<tr>\n<td style=\"border:1px solid #d9e1e8;padding:9px 12px\">Representative voltage\/current records with intervals<\/td>\n<td style=\"border:1px solid #d9e1e8;padding:9px 12px\">Shows the data set behind the request.<\/td>\n<\/tr>\n<tr>\n<td style=\"border:1px solid #d9e1e8;padding:9px 12px\">Chiller, AHU, pump, and fan operating-state log<\/td>\n<td style=\"border:1px solid #d9e1e8;padding:9px 12px\">Links each record to a terminal condition.<\/td>\n<\/tr>\n<tr>\n<td style=\"border:1px solid #d9e1e8;padding:9px 12px\">Existing capacitor, reactor, filter, and protection information<\/td>\n<td style=\"border:1px solid #d9e1e8;padding:9px 12px\">X\u00e1c \u0111\u1ecbnh c\u00e1c r\u00e0ng bu\u1ed9c t\u00edch h\u1ee3p.<\/td>\n<\/tr>\n<tr>\n<td style=\"border:1px solid #d9e1e8;padding:9px 12px\">Proposed equipment room, cooling, cable, and communication limits<\/td>\n<td style=\"border:1px solid #d9e1e8;padding:9px 12px\">Tests whether an installation concept is practical.<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p style=\"margin:0 0 16px;line-height:1.7\">CNBYG can discuss whether its product line fits a defined harmonic-current scope. It cannot promise airport uptime, passenger comfort, safety approval, code compliance, or a guaranteed electrical result from a general guide. Use <a href=\"https:\/\/cnbygele.com\/vi\/contact-us\/\">the terminal project information form<\/a> to begin a scope discussion.<\/p>\n<h2 style=\"margin:42px 0 14px;scroll-margin-top:96px\" id=\"frequently-asked-questions\">C\u00e1c c\u00e2u h\u1ecfi th\u01b0\u1eddng g\u1eb7p<\/h2>\n<h3 style=\"margin:28px 0 12px\">Why is a drive-terminal record not the same as a PCC record?<\/h3>\n<p style=\"margin:0 0 16px;line-height:1.7\">The drive-terminal record describes a local electrical location. A PCC record is taken at an agreed system boundary and may include the combined effect of multiple loads and the supply arrangement.<\/p>\n<h3 style=\"margin:28px 0 12px\">Which airport HVAC operating states should be logged?<\/h3>\n<p style=\"margin:0 0 16px;line-height:1.7\">Log the running chiller, air-handler, pump, and fan groups, their staging or speed changes, the time basis, major coincident loads, and any relevant standby-source arrangement.<\/p>\n<h3 style=\"margin:28px 0 12px\">Can connected motor kW determine an AHF or APF size?<\/h3>\n<p style=\"margin:0 0 16px;line-height:1.7\">No. A review needs measured current behavior, an operating-state record, the proposed connection point, and a defined objective before capacity is discussed.<\/p>\n<h3 style=\"margin:28px 0 12px\">Does an IEEE reference make a terminal result compliant?<\/h3>\n<p style=\"margin:0 0 16px;line-height:1.7\">No. The applicable boundary, data set, contractual requirement, network conditions, and acceptance process must be established for the specific project.<\/p>\n<h3 style=\"margin:28px 0 12px\">What should be included with an airport terminal HVAC harmonic inquiry?<\/h3>\n<p style=\"margin:0 0 16px;line-height:1.7\">Include the one-line diagram, nominal system information, meter and CT locations, representative records, HVAC operating-state log, existing equipment, protection details, and installation constraints.<\/p>\n<h3 style=\"margin:28px 0 12px\">Does this guide guarantee an airport operating result?<\/h3>\n<p style=\"margin:0 0 16px;line-height:1.7\">No. It supports a measurement-led project discussion and does not replace a protection study, utility review, code review, safety process, or acceptance test.<\/p>\n<h2 style=\"margin:42px 0 14px;scroll-margin-top:96px\" id=\"references\">T\u00e0i li\u1ec7u tham kh\u1ea3o<\/h2>\n<ul style=\"margin:0 0 18px 1.2em;line-height:1.7\">\n<li style=\"margin:0 0 8px\"><a href=\"https:\/\/standards.ieee.org\/ieee\/519\/5892\/\" rel=\"nofollow noopener\" target=\"_blank\">IEEE 519 \u2014 Ki\u1ec3m so\u00e1t s\u00f3ng h\u00e0i trong h\u1ec7 th\u1ed1ng \u0111i\u1ec7n<\/a><\/li>\n<li style=\"margin:0 0 8px\"><a href=\"https:\/\/www.nema.org\/standards\/view\/motors-and-generators\" rel=\"nofollow noopener\" target=\"_blank\">NEMA MG 1 \u2014 \u0110\u1ed9ng c\u01a1 v\u00e0 M\u00e1y ph\u00e1t \u0111i\u1ec7n<\/a><\/li>\n<li style=\"margin:0 0 8px\"><a href=\"https:\/\/www.energy.gov\/cmei\/ito\/industrial-technologies-office\" rel=\"nofollow noopener\" target=\"_blank\">Department of Energy \u2014 Industrial Technologies Office<\/a><\/li>\n<\/ul>\n<\/div>","protected":false},"excerpt":{"rendered":"<p>Airport terminal HVAC VFD harmonic work should begin with a measurement question, not a device choice. The record needs to state whether it represents one drive lineup, a mechanical-electrical room bus, or the terminal point of common coupling (PCC), and it needs to identify the operating state that produced it. Chillers, air-handling units, pumps, cooling-tower [&hellip;]<\/p>\n","protected":false},"author":3,"featured_media":1309,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"_gspb_post_css":"","footnotes":""},"categories":[1],"tags":[],"class_list":["post-2355","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-blog"],"blocksy_meta":{"styles_descriptor":{"styles":{"desktop":"","tablet":"","mobile":""},"google_fonts":[],"version":7}},"acf":[],"amp_enabled":true,"_links":{"self":[{"href":"https:\/\/cnbygele.com\/vi\/wp-json\/wp\/v2\/posts\/2355","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/cnbygele.com\/vi\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/cnbygele.com\/vi\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/cnbygele.com\/vi\/wp-json\/wp\/v2\/users\/3"}],"replies":[{"embeddable":true,"href":"https:\/\/cnbygele.com\/vi\/wp-json\/wp\/v2\/comments?post=2355"}],"version-history":[{"count":1,"href":"https:\/\/cnbygele.com\/vi\/wp-json\/wp\/v2\/posts\/2355\/revisions"}],"predecessor-version":[{"id":2537,"href":"https:\/\/cnbygele.com\/vi\/wp-json\/wp\/v2\/posts\/2355\/revisions\/2537"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/cnbygele.com\/vi\/wp-json\/wp\/v2\/media\/1309"}],"wp:attachment":[{"href":"https:\/\/cnbygele.com\/vi\/wp-json\/wp\/v2\/media?parent=2355"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/cnbygele.com\/vi\/wp-json\/wp\/v2\/categories?post=2355"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/cnbygele.com\/vi\/wp-json\/wp\/v2\/tags?post=2355"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}