A:Product Introduction: 　 DSHD-421 Insulating Oils Volumetric Resistivity Tester is a new instrument specially developed for resistivity determination using the active bridge principle as per the Industry Standard of People’s Republic of China DL/T421-91 “Test Method for Volume Resistivity of Insulating Oils”. Equipped with parameters measurement system and oil cup heating control system DSHD-421 Insulating Oils Volumetric Resistivity Tester can time, read readings and save test data automatically. So as to achieve the advantages of simple structure, excellent linearity, high sensitivity, stability and safety. Compared with the instrument using voltage or current method, the better it is. Excepting to determine the volume resistivity of insulating oils, DSHD-421 Insulating Oils Volumetric Resistivity Tester can also used to determine resistivity of transformer oil and lubricating oils. Further more,DSHD-421 Insulating Oils Volumetric Resistivity Tester is the best choice to determine volume resistivity of lubricating oils in the power industry, petroleum industry, scientific research institutes, and relative factories and companies. B: Main technical specifications and parameters: 　(I) Operation condition 　1. Ambient temperature: 0℃～40℃ 　2. Relative humidity: ≤85% 　3. Power supply: AC 220V±10%, 50Hz±1Hz 　(II) Measurement parameters 　1. Measurement voltage: DC 500 V 　2. Measurement range: 10 8 ～19.99×10 13 Ω·cm 　3. Repeatability: 　(1) ＞1012 Ω·cm: ≯25% 　(2) ＜1012 Ω·cm: ≯15% 　4. Heating power for temperature control: 300 W 　5. Temperature controlling range: 30℃～100℃ 　6. Temperature controlling accuracy: ±0.5℃ 　7. Measurement error: ≤±10% 　8. Measurement electrode cup: 3 pieces