High Voltage is a term generally used when a voltage exceeds 1000 Volts AC or 1500 Volts DC. High voltage applications can be found across the world such as in power generation, power distribution, rail networks, petrochemical refineries, commercial and industrial properties to name a few.
Why is high voltage more dangerous?
While low voltage electricity can be dangerous and can without doubt be deadly, the energy levels seen in high voltage systems represent a significantly increased hazard. Electrocution and serious burns can be received either by electricity flowing through the body or by arcing.
Many people mistakenly believe that the only way to be harmed by electricity is if you touch live parts, but high voltage electricity can travel through the air, this effect is called arcing. It is for this reason that high voltage test equipment usually has long probes ensuring a safe distance between the user and the system under test.
It is important to note that high voltage testing is extremely dangerous and should only be performed by competent persons who are fully instructed in the safe systems of work for the type of system being worked on. All hazards should be assessed and controlled (locking off, signage, PPE ETC). Never attempt any work on or near high voltage systems without the express permission of the system operator or owner. If in doubt you should not proceed; you should address the areas of doubt beforehand.
High Voltage Testing
There are many forms of testing that can be carried out on high voltage systems, but by far the most common is voltage detection or voltage indication, this is the process of checking that a voltage is present or not in a particular part of a high voltage system. Although under some circumstances work is carried out on high voltage systems while they are ‘live’, it is usually a requirement that the system is made ‘dead’ by a process called safe isolation before any work is carried out on, or near high voltage systems. Voltage detectors or indicators are therefore required to confirm that there is no voltage present at the point of work, after safe isolation and before work is carried out.
The Seaward KD1E is a highly robust and portable AC/DC HV Potential voltage indicator that includes both neon and digital systems to confirm the presence of voltage on earthed neutral electrical systems up to 11kV.
Conforming in design lengths to recommended creepage, clearance and safety standards, the KD1E Series features high grade PVC tubing and incorporates totally encapsulated resistor chains.
Seaward’s high voltage test range is designed for use on power system voltages of up to 33kV and includes ergonomically designed portable neon and digital voltage indicators, capacitive voltage indicators, circuit phasing equipment, insulator leakage detectors and current clamps this helps you to have the correct instrument for your needs.
Is an indicator enough?
To prove that the detector or indicator is working we need to have a known source on which to test safely, this function is usually performed by a device called a ‘Proving Unit’ like Seaward’s PH3. The Proving Unit is a battery powered device that generates a high voltage which can then be used to test the operation of the detector or indicator before and after proving ‘dead’. The three-step safe isolation process is designed to reduce the risk of an incorrect reading or indication, which could lead you to believe that a system is ‘dead’ when in fact it still poses a danger. This outcome could result from testing with a faulty detector or indicator which fails to light when connected to a ‘live’ circuit or even a detector or indicator which fails during the testing process. Only by proving before the test do we know that the detector or indicator is working and then by re-proving again afterwards do we know that it was still working at the time of test, giving us the confidence that the system is actually safe to work on.
The right tool for the job
It is of great importance to have the correctly rated detector/indicator and proving unit to work with each other but also for the application that they are to be used in. It goes without saying that you should never use one that is not rated for the system that you will be working on.