The Kyoritsu 3125 is a digital, high voltage device capable of testing insulation resistance in various voltages. This megohmmeter makes for a very unique tester as it features different testing modes while having additional capabilities which put you one step ahead. This device makes safety and accuracy the most important factors for a successful test. It packs some pretty useful, high-tech features which we are going to explore today.

kyoritsu 3125

Auto Power-off

This function enables the device to turn off itself automatically if a button press or a change of function doesn’t occur in the course of 10 minutes. The auto power-off function exists in order to preserve battery life thus extending the operating time of the Kyoritsu 3125a. It’s important to know that if you continuously press any buttons – the 10-minute window gets restarted every time you press a button or change a function.


When the Kyoritsu 3125a measures a capacitive load, the electrical charges that have been stored into the capacitive circuits get emptied (discharged). The discharge process is usually shown on the display, so the user knows when he is able to start measuring again. This function saves you time very seamlessly as you don’t need to do this yourself by pressing various buttons after every measurement.


Judging by the name of this feature, you may be thinking that you won’t have to do anything on this device except for holding it. Of course, that isn’t true but this next feature makes it easier for you to operate it by automatically measuring two types of tests. When both the polarization index (PI) and the dielectric absorption ratio (DAR) are measured, the results automatically appear on the display. The measuring range of the Kyoritsu 3125a starts from 30V and goes up to 660V both in AC and DC.

Software Features

The Kyoritsu 3125a has other software-related features that offer an even better user experience. The live voltage warning feature notifies you both on the display and audibly in real-time about the amount of voltage in the circuit. The bar graph indication is also displayed on the side of the display which has a backlight function – ideal when working in areas with dimmed lights or at nighttime. The indication of the output and the discharge voltage is also displayed on the screen. There’s a filter feature that enables the device to measure more stability by reducing the interference of electrical noise.