There can be no mistake that electrification in automotive applications is here to change the world of transportation as we know it. Whether we utilize electrification to assist or replace the internal combustion engine, modern vehicles will include additional high voltage wiring and components that, at some point in their service life, may require maintenance, diagnosis or repair.

Electrified powertrains should not be feared but more so relished for the diagnostic opportunities they present such as charging errors, contactor failure, inverter malfunctions, insulation and earth bonding faults.

Naturally, training is fundamental to diagnosis and the electrified powertrains are no exception as we require new skill sets to acquire revised measurement techniques using alternative test equipment.

One such piece of alternative test equipment, that will be new to many, is the Two-pole Voltage Detector from Pico Auto, which is designed to categorically prove the absence of voltage (zero potential) when following the correct test procedure.

Zero potential testing is arguably one of the most important measurements you will ever make, as your life literally depends on it! In order to qualify the absence of voltage a robust test sequence, in conjunction with the TA466 Two-pole Voltage Detector, will ensure beyond any doubt that your vehicle/machine is shut down.

So how can you use the Two-pole Voltage Detector to qualify the absence of voltage?

The Two-pole voltage detector is the go-to tool once you have followed the manufacturer procedure for shutting down the vehicle/machine you want to test. At some point during the shutdown process, we are asked to qualify the absence of voltage at the specified measurement point.

Before attempting the following test, please follow the relevant safety procedures with the appropriate PPE:

  1. Reach for the Two-pole Voltage Detector and inspect the device for signs of damage.

The attached test leads of the voltage detector are double insulated and black in colour. Do not use the voltage detector if the test leads reveal the white inner cable.

  1. Press the button at the base of the voltage detector to illuminate the LED torch above the LCD display.
  2. Join the voltage detector’s probe tips together. The device will respond by illuminating the display and sounding an alarm.
  3. We now place the probe tips across a known good low-voltage source, such as a 12 V battery. The display will illuminate blue (indicating a safe working voltage) and display the acquired value.
  4. You can now use the voltage detector to measure the high-voltage test points of the vehicle/machine under test as per the manufacturer’s instructions.

If no voltage is present, the voltage detector will not respond. If it detects a voltage between 3 and 36 V AC/DC the display will illuminate blue. Should it detect a dangerously high voltage (above 36 V AC/DC) the display will illuminate red and the alarm will sound.

  1. The final check is to qualify that the voltage detector is functioning correctly by once again measuring across a known good low voltage source. If the display illuminates blue it confirms the integrity of the device.

To watch the entire procedure above, please visit the new Electric Vehicle Guided Tests within PicoScope 7 version 7.0.59 or later. You can download the latest version of the software here. In the Guided Test menu, click on the Electric Vehicle icon, select Safety Tests > 0 V potential and open the “Guide and settings file”. Within this Guided Test you will find a link to a supporting video describing the application of the voltage detector. 

As you can see, zero-volt potential testing requires a disciplined and robust measurement routine to ensure beyond a reasonable doubt that the acquired results are both accurate and verified.

So, what are the advantages of the Two-pole Voltage Detector and why can I not just use my multimeter?

The short answer here is that you can!

However, the potential for erroneous test results increases given the number of the variables presented to the user of the multimeter.

Whether you are a Master Technician or an Apprentice, the potential for mistakes in a pressurised working environment is inevitable (we are all human).

Let’s assume you apply the multimeter to the relevant high-voltage test points of a vehicle but you have set the dial to display AC voltage!

Or how about the test leads of the multimeter, what if they are not in the correct ports on the meter?

In both cases, the multimeter will read either low or no voltage suggesting the vehicle is shut down and safe to dismantle! The word “shocking” does not do such a measurement error justice!

The following video describes the numerous pitfalls of using a multimeter instead of a Two-pole  Voltage Detector to confirm the absence of high voltage.

I hope you found this information useful. If you want more information on our EV measurement solutions and a glimpse of how automotive electrification is changing our world, I suggest the following links: Electric Vehicle (EV) kits and accessories on our website and Welcome to EV on the Automotive Support Forum.

Take care,

Steve