The Methods Of Measuring The Residual Voltage And The Key Technology Of A New Residual Voltage Measurement Device

The residual voltage is the voltage remained between the plug pins immediately after the plug of the device disconnected from the power supply, or the voltage remained in the energy storage components such as capacitors immediately after the electrical equipment disconnected with the power grid. Setting a limit value for the residual voltage and the residual energy is aimed at guaranteeing the security for the patients, operators or others by preventing them from the danger of electric shock when they touch the charged components. Therefore accurate measurement of the residual voltage of the medical device is of significant importance.This paper developed a new residual voltage measurement device by studying the methods of measuring the residual voltage. This device is composed of a singlechip microcomputer based control and data processing unit, and peak detection circuits. First, the devices to be measured are connected to the power supply, and the peak detection circuits are used to detect the peak voltage accurately. Then the singlechip microcomputer emits a control signal to force the driving relay circuit to be disconnected from the power supply. Second, the voltage driver is employed to sample the residual voltage remained between the plug pins. This sampling voltage is transmitted to a voltage follower, the output of which is converted by an ADC and then transmitted to the singlechip microcomputer unit, where the data is processed, stored and displayed. The device will give an alarm when the residual voltage is beyond the standard value.This study provides a solution to a key technologic problem, that is, to shutoff the power supply at the peak accurately, which can be accomplished by designing a key zero-crossing detection circuit combined with an adjustable delay circuit. This new residual voltage measurement device has good repeatability and stability, and can overcome the existing devices’deficiencies such as inability to shutoff the power supply at the peak accurately, limitation of the testing impedance and inability to display the discharging curve.