Hey everyone, looking for a cost-effective harmonic distortion analyzer to test THD of inverter output sine waves—nothing too expensive. Thanks!
You can use an oscilloscope.
Pro, does a digital oscilloscope have this function?
All include power supply analysis
This isn’t enough to convince the customer, right? Do you have any other recommendations, like those with a pointer 
?
Buy a used Yokogawa power analyzer
WT1806E and similar models currently still cost fifty to sixty thousand secondhand.
Oscilloscopes offer higher cost-performance; the SDS804 can analyze harmonics, and with probes, the total cost doesn’t exceed 10,000.
This is for audio analysis; in practice, it’s far inferior to power dividers. Power dividers cost six figures.
Cost-Effective THD Analyzers for Inverter Sine Wave Measurement
For measuring Total Harmonic Distortion (THD) of inverter sine wave outputs, I’ve compiled a curated list of cost-effective options tailored to embedded engineers, balancing accuracy, features, and budget. All options below handle inverter-specific challenges like PWM harmonics and variable frequency outputs.
Quick Recommendations by Budget & Use Case
| Category | Best Pick | Price Range | Key Strengths |
|---|---|---|---|
| Handheld (Field/Portable) | UNI-T UT283A+ | $250–$350 | Single-phase, THD up to 51st harmonic, USB data logging |
| Benchtop (Lab/Dev) | GW Instek GPM-8213 | $600–$800 | 6kHz bandwidth, 19 power parameters, THDV/THDI |
| USB/PC-Based (DIY/Automated) | Virtins VT RTA-168C + Voltage Divider | $300–$400 | Software-defined, FFT analysis, sub-0.01% THD resolution |
| Budget All-Rounder | UNI-T UTE9802+ | $300–$400 | 4-window display, PLL sync, 0.4% accuracy |
Detailed Product Recommendations
1. Handheld Power Quality Analyzers
UNI-T UT283A+ (Discontinued, but widely available used)
- Price: ~$250 (new), ~$150 (used)
- THD Measurement: 0.0%–99.9%, ±(1%+5dgt) accuracy (Vrms > 50V)
- Harmonic Range: Up to 51st harmonic (step 0.5th for precision)
- Frequency Range: 40–400Hz (ideal for most inverters)
- Key Features: Trend/event capture, USB interface, SD card data logging, waveform display
- Best For: Field testing, on-site inverter commissioning, portable troubleshooting
UNI-T UT285C (Three-phase capable)
- Price: $350–$450
- THD Measurement: Same as UT283A+
- Harmonic Range: Up to 50th harmonic
- Key Features: 4-channel voltage/current waveform display, transformer K factor, short-term flicker (PST) measurement UNI-T Meters
- Best For: Three-phase inverter systems, power quality audits, comprehensive distortion analysis
2. Benchtop Power Meters with THD Analysis
GW Instek GPM-8213
- Price: $600–$800
- THD Measurement: THDV and THDI (total harmonic distortion for voltage and current)
- Frequency Bandwidth: DC~6kHz (handles PWM inverter switching noise)
- Key Features: 4" TFT LCD, five-digit display, 19 power parameters, integral measurement (W-h/A-h), front/rear panel inputs gwinstek.com
- Accuracy: Voltage/current: ±0.1%, Power: ±0.2%
- Best For: Lab-based inverter development, production testing, high-precision THD validation
UNI-T UTE9802+
- Price: $300–$400
- THD Measurement: Harmonic analysis up to 50th order
- Key Features: PLL synchronization (precise harmonic capture), multi-window display, automatic range selection, RS-232/RS-485 (Modbus/SCPI)
- Frequency Range: 40–400Hz
- Best For: Budget-conscious lab testing, embedded system integration, automated test setups
3. USB/PC-Based THD Analyzers (Software-Defined)
Virtins VT RTA-168C + Custom Voltage Divider
- Price: VT RTA-168C ($309.95) + Voltage Divider ($50–$100)
- THD Measurement: THD, THD+N, SINAD (down to 0.001% with proper setup)
- Key Features: PC-based real-time analysis, FFT up to 1MHz, 24-bit resolution, free software updates
- Frequency Range: 10Hz–40kHz (covers inverter fundamental and switching harmonics)
- Best For: DIY enthusiasts, embedded engineers, high-resolution THD analysis, data visualization
Alternative: Use Your Oscilloscope + Power Analysis Software
- Price: $0–$829 (if you already own an oscilloscope)
- Option: UNI-T MSO5000HD-PWR software ($829) or free alternatives like Siglent SDS-PWR
- THD Measurement: Up to 31st harmonic (30Hz–450Hz fundamental)
- Key Features: Waveform capture, FFT analysis, power quality metrics
- Best For: Engineers who already own an oscilloscope, want to maximize existing equipment
4. Specialized Inverter THD Solutions
TTi HA1600A AC Line Harmonics Analyzer
- Price: $400–$500
- THD Measurement: THD-F (THD relative to fundamental)
- Key Features: Dual power cables (load supply independent), up to 16A RMS, 50/60Hz fundamental with ±0.1Hz accuracy
- Best For: Grid-tied inverter testing, compliance with utility THD standards (<5% for most applications)
Critical Selection Criteria for Inverter THD Measurement
- Bandwidth: Minimum 2kHz (preferably 5kHz+) to capture PWM switching harmonics
- Harmonic Order: At least 31st (ideally 50th+) for accurate low-distortion sine wave analysis
- Synchronization: Look for PLL or synchronous FFT to handle variable inverter frequencies
- Input Protection: CAT II 600V minimum (CAT III preferred) for safe inverter output measurements
- Accuracy: THD accuracy of ±1% or better for meaningful comparison to industry standards
Final Recommendations by User Scenario
- Embedded Engineer on a Tight Budget:
- Best Choice: UNI-T UTE9802+ ($300–$400)
- Why: Combines benchtop precision with affordability, offers remote control via Modbus/SCPI for automated testing
- DIY Inverter Builder/ Hobbyist:
- Best Choice: Virtins VT RTA-168C + Voltage Divider ($350–$400)
- Why: Software-defined flexibility, high-resolution analysis, and free software updates
- Professional Inverter Developer (Production/QC):
- Best Choice: GW Instek GPM-8213 ($600–$800)
- Why: Industry-standard accuracy, wide bandwidth, comprehensive power parameters, and reliable performance gwinstek.com
- Field Service Technician:
- Best Choice: UNI-T UT283A+ (used, $150–$250) or UT285C ($350–$450)
- Why: Portable, rugged, battery-powered, and designed for on-site troubleshooting UNI-T Meters
All recommended instruments will provide reliable THD measurements for inverter sine wave outputs, helping you optimize your design for efficiency and compliance with power quality standards.