THE OUTRAM FLM PRODUCT FUNCTION
The Outram Fault Level Monitor uses natural disturbances observed on the network to derive its results.
How are the Fault Level predictions derived?
Measuring natural disturbances of as little as 0.15% the PM7000 FLM delivers three internal predictions
- Peak Fault Level 10ms after fault – Upstream
- RMS Fault Level 90ms after fault – Upstream (90ms time is variable)
- Peak Fault Level 10ms after fault – Downstream
These predictions are then converted into appropriate Fault Level values.
- Composite Fault Level results: The aggregation of multiple predictions over a given time period resulting in the most solid result of the Fault Level at that measurement point on the network.
- Real Time Fault Level results: The most recent results generated are given in tabular format along with a confidence weighting and time stamp.
- Fault Level Trend over time: Both peak and RMS fault level predictions are mapped over the length of the recording for a trend and comparative overview (e.g. line graph).
N.B. Performance of the FLM is based on the strength and the type of disturbances observed on the network, therefore if no or only very small, disturbances are observed then no results can be generated.
So how does it work?
“The Outram FLM works using a novel, patent-pending algorithm to determine worst case fault current, separating out peak ‘make’ current, RMS ‘break’ current and contributions from downstream motors.
This is achieved by extracting the tiny characteristics of interest from voltage and current signals at the arbitrary times at which natural disturbances occur, e.g. tap changes and load switching. The instrument distinguishes the various components capable of delivering the fault level results, processing these mathematically to optimise signal to noise then filtering and computing the desired Fault Level values from this data.
This innovative solution means that high quality results can be obtained from voltage disturbances of as little as 0.15%. No previous knowledge of the network is required and the FLM can be deployed at any voltage level assuming the necessary CTs and VTs are in place.”
John Outram, Managing Director, 2012