What Is a Pressure Tester?
Pressure testers are used to check whether various types of equipment, such as home appliances, have dielectric strength when high voltage is applied to them.
If the equipment does not have dielectric strength and dielectric breakdown occurs when high voltage is applied, the user may be electrocuted or disabled. As well, a fire may occur, or in the worst case, the equipment may explode.
To avoid such a situation, the laws stipulate the withstand voltage that must be observed for each device.
Pressure testers are used to test whether the equipment meets the withstand voltage standards.
Uses of Pressure Testers
If a person touches a device that has suffered a dielectric breakdown, a path is created for an electric current to flow through the device. The current flows from the device to the earth via the human body and can cause a person to receive an electric shock.
A countermeasure against electric shock is to insulate the equipment completely so that the current does not flow out of the equipment to the outside. Another method is to provide a current path with a resistance value as close to zero as possible in case the current flows out of the equipment. Generally, these measures are taken at the equipment design stage.
As a result of the design, the equipment is tested using a pressure tester to see if it has the insulation to withstand voltage as designed.
Principle of Pressure Testers
Pressure tester testing is performed by applying an AC or DC voltage of several kilovolts, which is several tens of times the voltage normally handled.
Specifically, a short circuit is made between two power supply terminals and a high voltage is applied for a certain period between the terminals and the exterior of the equipment, such as the housing or cabinet.
Equipment operation is checked after the application of high voltage, and the equipment passes the test if the same level of operation can be confirmed as before the test.
Pressure testers are required to conduct tests in accordance with safety and other laws to confirm that equipment meets the standards, so accurate testing is necessary. The test is meaningless unless the applied voltage value and the applied time are accurate.
For this reason, pressure testers must be calibrated periodically. This involves preparing a standard device that has been verified to show correct values, checking to see if there are any deviations in the values shown by the testing device compared to the standard device, and making adjustments. Generally, a sticker with the date of calibration is attached to the calibrated tester to ensure correct management of the equipment.