VFD Energy Saving on Pumps and Fans: Affinity Laws
The affinity laws show why cutting a centrifugal pump or fan's speed 20% can cut its power draw nearly in half, and where that cube-law estimate breaks down in real...
9 min read
Technical
VFD guides
Guides and notes on industrial electrical and automation parts: selection, wiring, settings and ordering.
- Articles
- 46
VFD Communication: Modbus, PROFINET and EtherNet/IP
How VFDs exchange data with a PLC over Modbus RTU, PROFINET, EtherNet/IP, and EtherCAT, and how to pick the right protocol for the plant network.
9 min read
VFD Enclosure Ratings: IP20, IP55 and Cabinet Cooling
IP20, IP55 and IP66 enclosure ratings for VFDs, NEMA/UL equivalents, and how to size cabinet cooling so the drive doesn't overheat or corrode.
8 min read
VFD Overload: Normal Duty vs Heavy Duty Ratings
A field guide to VFD Normal Duty and Heavy Duty overload current ratings — what the percentages mean, why the same frame gives less kW in HD, and how to...
9 min read
VFD Motor Bearing Currents and Shaft Grounding
PWM common-mode voltage induces shaft voltage on VFD-fed motors, which discharges through the bearing film as EDM pitting and fluting unless a shaft grounding ring, insulated bearing, or common-mode filter...
9 min read
VFD Output Filters: dV/dt, Sine Wave and Cable Length
How reflected-wave voltage forms on VFD output cables and how to choose between a dV/dt reactor, a sine-wave filter, and cable-length limits.
10 min read
VFD Carrier Frequency and Switching Losses
How VFD carrier frequency trades off audible noise, IGBT switching losses, and continuous current rating, and how to pick a setting without silently derating the drive.
8 min read
VFD Braking: Dynamic, Regenerative and DC Injection
How dynamic braking, regenerative active front ends, and DC injection each manage DC bus overvoltage during motor deceleration, with resistor sizing and load-type selection guidance.
11 min read
What Is Direct Torque Control (DTC) in a VFD
Direct Torque Control estimates stator flux and torque directly from voltage and current, giving ABB drives millisecond torque response and low-speed torque without an encoder.
8 min read
VFD Control Methods: V/f, Vector and DTC Compared
A side-by-side comparison of V/f, vector, and DTC control in VFDs, covering low-speed torque, dynamic response, tuning effort, and which method fits which load.
9 min read
VFD vs Servo Drive: Key Differences
A side-by-side comparison of VFD and servo drive motor type, feedback, dynamic response, overload rating, cost, and applications for industrial engineers.
10 min read
How a VFD Works: PWM and V/f Control Explained
A VFD synthesizes variable-frequency AC through PWM switching and holds the volts-per-hertz ratio constant under scalar control to keep motor flux stable across the speed range.
9 min read
Main Components of a VFD: Rectifier, DC Bus and Inverter
A technical breakdown of the rectifier, DC bus, and inverter stages inside a VFD, including common failure modes and field-observed faults.
9 min read
VFD vs Soft Starter: Key Differences for Motor Control Engineers
Compare VFD vs soft starter for motor control: starting torque, speed regulation, harmonics, IEC standards, and total cost of ownership. Shop at Stoklink.
15 min read
Variable Frequency Drive Selection Checklist for Engineers and Buyers
VFD selection checklist for engineers: load profile, sizing, harmonics, EMC, derating, and brand comparison across ABB and Schneider. Shop at Stoklink.
18 min read
How to Size a Variable Frequency Drive for an AC Motor: Complete Guide
Size your VFD correctly with our complete guide covering FLA calculation, duty cycle, derating, harmonics, and brand-specific sizing tables. Shop at Stoklink.
22 min read
Variable Frequency Drive Voltage and Current Ratings Explained
Understand VFD voltage and current ratings, sizing rules, IEC and NEMA standards to match drives with motors and prevent costly failures. Shop at Stoklink.
19 min read
VFD Harmonics and EMC Filter Requirements: Engineering Guide
VFD harmonics and EMC filter guide covering IEC 61000-3-12, IEEE 519, filter categories C1-C4, line reactor sizing, and installation tips. Shop at Stoklink.
20 min read
Types of Variable Frequency Drives: VSI, CSI, PWM and Matrix VFDs Guide
Compare VFD types including VSI, CSI, PWM, and matrix converters with selection criteria, harmonic data, and real installation examples. Shop at Stoklink.
16 min read
IEC and NEMA Standards for Variable Frequency Drives Explained
VFD standards demystified: IEC 61800 series, NEMA ICS 7, IEEE 519 harmonics, IP and NEMA enclosure ratings, plus SCCR procurement tips. Shop at Stoklink.
19 min read
What Is a Variable Frequency Drive and How Does It Work in Industry
Learn how a VFD works, from rectifier to PWM inverter, plus sizing rules, IEC standards, and field tips for pumps, fans, and conveyors. Shop at Stoklink.
19 min read
Variable Frequency Drive Guide: How VFDs Work, Selection, Install and Maintenance
Variable frequency drive guide covering VFD operation, sizing by load type, IEC 61800 compliance, installation, harmonics, and maintenance. Shop at Stoklink.
32 min read
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