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Soken DAC-LFM-3 - Low Frequency C & tan δ Meter

Low Frequency C & tan δ Meter


Category : Dielectric loss tangent testing instrument

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DAC-LFM-3 is designed to measure tan δ and capacitance of test samples with a built-in very-low-frequency power source 0.1Hz or 0.01Hz. The meter can be used for various applications, such as Drying process control of oil-filled or mineral insulated cables, Failure point identification of optical fiber submarine cables, Insulation diagnosis of commercial frequency power cables.   Applications Drying process control of oil-filled or mineral insulated cables Failure point identification of optical fiber submarine cables Insulation diagnosis of commercial frequency power cables.



  • Drying process control of oil-filled or mineral insulated cables
  • Failure point identification of optical fiber submarine cables
  • Insulation diagnosis of commercial frequency power cables



The following schematic diagram shows the measuring circuit of Model DAC-LFM-3.

The low-frequency signal generated at the oscillator is power-amplified to supply the reference voltage E. The standard capacitor Cs detects the reference current Is = jωCsE. Analog values of the reference current flowing through the Cs and the current flowing through the test object Cx are multiplied after they are converted into digital data. Finally, parameter analysis of the corresponding equivalent circuit is performed to obtain the true values of tan δ and electrostatic capacitance.

In general, the insulator (2) is considered as dielectric, and measure the electrostatic capacitance and tan δ between the central conductor (1) and the shielded conductor (3). Measurement is possible by making either connection: connect (1) to HIGH terminal and (3) to LOW terminal, or connect (1) to LOW terminal and (3) to HIGH terminal.


Connecting Diagrams

Measurement of grounded specimens

Measurement of ungrounded specimens


Measuring Method

A TFT LCD along with a touch keyboard assures the comfortable operation of Model DAC-LFM-3. On the operation screen, you can see all the information necessary for measurement, and you can readily follow the progress of measurement operation. When you touch an operation parameter on the screen, a corresponding pop-up window appears, on which you can readily specify the desired data setup 

  1. [CAPACITANCE]: Electrostatic capacitance, 6 digits of full scale
  2. [DIELECTRIC LOSS (%)]: Tan δ, 6 digits of full scale
  3. [OUTPUT VOLTAGE (V)]: Output voltage on scale bar
  4. [MEASURE MODE]: Selection of measuring equivalent circuit
  5. [MODE]: Selection of measuring mode
  6. [OUTPUT IMPEDANCE]: Selection of output impedance
  7. [tan δ RANGE]: Selection of analog data output range
  8. [SELF CHECK]: Self Test
  9. [CHARGE TIME]: Selection and display of charging time
  10. Selection of measuring electrostatic capacitance range
  11. [LOCAL / REMORT]: Interface condition
  12. [WORK]: Displayed in red when the testing voltage is turned on.


Option Software

With this optional software, you can display time-series data of tanδ and electrostatic capacitance.

Note: This sample program uses VISA (Virtual Instrument Software Architecture) for the transmission of messages to and from the measuring instrument. VISA is a registered trademark of National Instruments Corporation.

OS: Windows 2000, XP, Vista 32 bits Driver: USB Serial Converter from FTDI (Future Technology Devices International Ltd.)

  • Full digital processing using a 32-bit MPU
  • Comfortable operation with a TFT LCD and a touch keyboard
  • Built-in very-low-frequency power source
  • Compact and lightweight
  • USB interface equipped standard



MassAbout 15 kg
Dimensions200 (H) × 430 (W) × 450 (D) mm, excluding projections
Operating environmentOperating temperature range; 10ºC - 40ºC
Operating relative humidity range; 0% - 80% (at 35ºC or lower)
Power consumptionMaximum 125 VA, standard about 60 VA
Driving power source(100 - 240 VAC) ± 10%, 50/60 Hz
External interfaceUSB
External analog outputElectrostatic capacitance and dielectric loss
Charging time setting0 - 99 s in increments of 1 s on the LCD screen
Output voltage displayLCD bar graph, Indicating range: ± 150 VDC
Output impedanceLOW: 10 kΩ ± 5%
MID: 50 kΩ ± 5%
HIGH: 100 kΩ ± 5%
Measurement terminalsTwo-terminal configuration (HIGH and LOW); TXA104-BR terminals plus a grounding terminal (GND)
Measuring modeManual selection between parallel equivalent circuit and series equivalent circuit
Measuring voltage100 Vrms ± 10%, Stability: ± 0.1%/ºC, Output current: Maximum 20 mA
Measuring timeWithin 30 s, excluding charging time
Measuring frequency0.1 Hz ± 3%, Stability: ± 500 ppm/ºC
Measurement itemsC (electrostatic capacitance) and D (tan δ)
(1) Electrostatic capacitance: 100.00 pF - 100.000 µF Manual and automatic selection of capacitance range
(2) Tan δ: 0.010% - 999.999%

Do you have a Low Frequency C & tan δ Meter that needs to be calibrated?

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