If you are still using traditional Rogowski Coil Sensors, read on to see how you could vastly – and easily – improve the condition monitoring of your high voltage assets.

What are Rogowski Coils Sensors?

First presented in 1912, the Rogowski sensor (below) is an air-core coil that measures AC in electrical assets and cables. They may require their own power supply and PD data interpretation is often difficult. They are still used today, but more and more asset managers and engineers are upgrading to modern alternatives in order to have better sight of their network’s condition.

What is HVPD’s modern alternative?

HVPD’s High Frequency Current Transformer (HFCT) sensors are used to measure Partial Discharge in power cables and in remotely-connected HV plant such as rotating HV machines and transformers. The sensors are attached around the cable’s earth connections in the switchgear, rotating machine or transformer’s HV cable terminal box, on the cable itself, or on each phase core.

The HFCT sensors work on a similar principle to the old Rogowski Coil sensors, but the HFCTs have a ferrite core rather than an air core. This contributes to them being 30 times more sensitive to PD pulses omitted by MV and HV machines.

Why should you upgrade?

There are many reasons why you should upgrade from out-dated technology to HFCT sensors, but the bottom line is that they are better at preventing catastrophic failures and unplanned outages.
As already explained, a ferrite core technology (HFCT) results in a sensor that is tens of TIMES more sensitive to PD pulses. This means that PD signals will be detected much earlier with HFCT sensors than with Rogowski sensors.

Transfer Impedance (TI) is a feature that highlights the sensitivity of the sensor. For inductive sensors such as Rogowski coils and HFCTs, TI should be known in order to accurately converse the HF current pulse (PD) into pC values. In many cases, the TI of Rogowskis in the field can be unknown or difficult to determine, creating a number of problems when it comes to analysing the severity of obtained results.

With HVPD’s HFCTs, TI is pre-defined, which makes the interpretation of results much more straight forward.

HVPD also boasts an ever-growing wealth of experience of measuring PD using HFCTs. This means that any future PD results obtained with HFCTs can be compared against a large database of similar assets. Hence, interpretation and expert recommendations are much more accurate and helpful to your CBM plan. With the improvements in the hardware, coupled with the industry-leading knowledge that HVPD’s experts hold, it really could be a simple decision to upgrade your existing sensors.

The best and most convenient time to make the change is during a planned outage. At your next outage, HVPD’s installation team can replace your old Rogowski sensors for modern HFCTs, and give you a better idea of your network’s condition.

Are you still using Rogowski Coil sensors? Protect your critical assets, and drop us a line to enquire today: sales@hvpd.co.uk

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