Table of Contents

Overview of Frequency Selective Multimeter

This portable frequency selective multimeter integrates voltage and current measurement functions, specially designed for power grounding grid field detection. With adaptive digital notch filtering technology, it strongly suppresses severe 50Hz power frequency electromagnetic interference on site.

It accurately tests step voltage, touch voltage, potential gradient and tower shunt parameters, supports 40–70Hz arbitrary frequency selection. Equipped with full-touch screen, wireless communication, USB data export and built-in printing functions, it features high measuring precision, large storage capacity and long battery life. Lightweight and fully compliant with domestic grounding testing standards, it is widely adopted for substation grounding acceptance, lightning protection inspection and power system routine maintenance.

Features and Main Functions

Excellent anti-interference performance

It adopts high-precision adaptive digital notch filtering technology to automatically track and suppress interfering frequencies, with a theoretical interference rejection ratio of nearly 1,000,000:1. Compared with imported frequency-selective voltmeters which only achieve a rejection ratio of several hundred times, this instrument can practically eliminate the impact of field interference.

Powerful comprehensive functions

It supports measurement of step voltage, touch voltage, transfer potential, potential gradient, tower shunt current and other grounding parameters.

Wireless data transmission for tower shunt current tests

Wireless data communication is available during tower diversion current measurement.

Automatic calculation of shunt-related parameters

The vector sum, total grounding current and shunt coefficient can be automatically calculated via the data save and delete buttons. Users can check how shunt vectors affect the shunt coefficient without tedious manual calculation.

Full-touch LCD display

Equipped with a large graphical touch operation screen, all test procedures are displayed clearly. Operators can master the whole testing process easily without professional training simply by touching the screen.

Historical data storage and printout

Built-in calendar chip and large-capacity memory allow permanent storage of test results. Historical records can be retrieved and printed with exact timestamps displayed.

Advanced data management system

Test data can be exported via USB flash drive to any computer. Dedicated PC software enables data viewing, management, as well as automatic generation of forms and formal test reports.

Simple automatic operation

The whole measurement process is controlled by a microprocessor. After selecting the corresponding measurement mode, the instrument will finish data measurement automatically.

Technical Specifications

Item	Specification
Voltage Measurement Range	0 ~ 200 V
Voltage Resolution	0.001 mV
Voltage Accuracy	±(2% of reading + 0.1 mV)
Current Measurement Range	0 ~ 20 A
Current Resolution	0.001 A
Current Accuracy	±(2% of reading + 0.01 A)
Selectable Frequency Range	Arbitrary frequency: 40 Hz ~ 70 Hz
Input Impedance	＞500 kΩ
Built-in Human Body Analog Resistance	1500 Ω ±5%
Wireless Transmission Distance	Line-of-sight: 5000 m Inside substation: 1000 m
Anti 50Hz Power Frequency Interference	Accuracy ≤5% under 10,000 times power frequency interference
Continuous Battery Working Time	8 ~ 12 hours
Charging Time	About 3 hours
Charging Power Source	AC 220V±10%, 50Hz / 60Hz
Overall Dimension	320 mm × 275 mm × 140 mm
Net Weight	3 kg

FAQ for Frequency Selective Multimeter

1. What is the main application of this frequency selective multimeter?

It is specially used for power system grounding grid testing, measuring step voltage, touch voltage, potential gradient and tower shunt current to evaluate grounding safety performance of substations.

2. How does the instrument suppress strong on-site 50Hz power frequency interference?

It applies adaptive digital notch filtering technology. The interference rejection ratio reaches nearly 1,000,000:1, and measurement accuracy stays within 5% even under 10,000 times power frequency disturbance.

3. What measuring functions does it support?

It can test AC voltage (0~200V) and AC current (0~20A), with optional arbitrary frequency between 40Hz and 70Hz to match different excitation signals.

4. Why is the built-in 1500Ω analog human resistance equipped?

It strictly simulates human body resistance specified in power industry standards, which is essential for accurate step voltage and touch voltage measurement.

5. What is the wireless transmission range?

Line-of-sight transmission distance is up to 5000 meters; the stable wireless distance inside substations is 1000 meters for long-distance tower shunt tests.

6. How about data storage and export methods?

It saves all test records with timestamps. Data can be printed directly via the built-in printer or exported via USB flash drive to PC for report generation with dedicated software.

7. Is the device easy to operate for field engineers?

It adopts full-touch graphical screen. The microprocessor completes automatic measurement after selecting modes, no advanced professional training is required.

8. Battery life and charging specifications?

Continuous working time: 8–12 hours; full charging takes around 3 hours with AC 220V power supply.

9. Is this instrument lightweight for outdoor field work?

Net weight is only 3kg with rugged portable case, compact size 320×275×140mm, greatly reducing field carrying burden.

10. Which industry standard does it comply with?

It fully meets the requirements of DL/T475-2017 Guide for Measurement of Parameters of Grounding Devices for power grounding acceptance and routine maintenance.

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