Future proof Energy Management solutionsFollow article
A critical part of any energy management system is the continuous measurement and monitoring of all energy parameters. In older developed plants, there is a real need for retrofitting current measurement equipment. The main challenge comes during installation, where the need to disturb or halt production can lead to expensive downtime.
Some traditional current transformer (CTs) suppliers have ‘retrofit kits’, which have a two-part or ‘split’ core. Compared to standard CTs, split-core transformers can be installed quickly as they can be easily opened and placed around the busbar. However, this method has certain disadvantages and it has remained essentially unchanged for the past 30 years.
Examples of these disadvantages are:
- When closing the housing, there is always an air gap that remains between the two moveable parts of the transformer core. This causes a power loss, so the transformer core needs to be quite large in order to compensate.
- Split-core CTs are difficult to install, especially when you have very little space between your bus bars.
- The price level of split-core transformers depends on both the size of the housing and on the rated power (VA).
- They are prone to magnetic saturation.
- They are limited to 50 or 60 HZ.
- They can only partially measure harmonics.
- There is always the potential danger of an open circuit voltage – which can be at kV levels.
A much smarter retrofit solution that does not suffer from any of these disadvantages is the Rogowski coil current transformer.
The Rogowski principle
On the market today there are various Rogowski coils with this increased accuracy. However, they are not suitable for continuous use in industrial applications without further optimisation:
- Along with the position error, there is also a potential transmission error of ± 5%.
- They lack options for mounting them on busbar or directly on the cable.
- The mV output signal does not correspond to the typical secondary current of a current transformer. It is, therefore, not suitable for direct processing.
- They have low-temperature resilience and the busbars can become very hot.
- They have low insulation resistance.
PACT RCP current transformers from Phoenix Contact are suitable for retrofit installations without any of the disadvantages shown above.
The PACT RCP system consists of the following components:
- A Rogowski coil, in three different lengths, for optimal adjustment to busbar and circular conductor sizes.
- A measuring transducer with a 1-amp AC output (version A) or a measuring transducer with a standard analogue signal output (version B)
- An optional mounting clamp for busbars
The coil measures alternating currents up to 4000 A, which are converted by the measuring transducer into a typical secondary current of 1 A or into a freely configurable analogue signal. This makes PACT RCP the universal, space-saving alternative to the standard current transformer for retrofit installation.
Version A has eight different current ranges, from 100 to 4000 A, which can be selected via DIP switches. The signal output takes place fully phase-correlated within a frequency range of 10 Hz to 5000 Hz.
Version B has a signal input and signal output which is freely configurable. The system operates in a frequency range of 10 Hz to 5000 Hz.
The optional mounting device ensures a lasting and secure fit of the coil even on very warm busbars.
Up until recently, option A was only available as a kit, meaning you had to buy both the coil and the transducer. However, that all changed in 2019 with the introduction of the EMpro energy meters from Phoenix Contact.
These meters are available with both a traditional CT input or with a direct input from a Rogowski coil. This means the overall costs involved to integrate these meters into a retrofit project are significantly reduced – due to the fact the transducer is no longer required!
The EMpro meters come with Modbus TCP as standard but can also have a secondary communication protocol, such as Modbus RTU, Profinet or EthernetIP. EMpro meters are set up very quickly via their pushbuttons or using their integrated web browser.
This year the range has been further expanded, with 24 VDC control options, REST API connectivity and with 2 versions for direct connection to the Cloud.
So Phoenix Contact has future proof solutions for all your Energy Management needs.
For further information or a demo please contact the Energy Management product manager Fraser Cowie on 07584 514963 or at firstname.lastname@example.org