General; Fault Locator Functionality; Off-Line Fault Location; Single-Ended Fault Location - Satec expertmeter PM180 Application Note

1 General

1.1 Fault Locator Functionality

The PM180 onboard fault locator provides distance to fault information in real-time. It
operates on fault events detected and recorded by the PM180 digital fault recorder
immediately as events happen.
The fault locator uses impedance-based fault location methods. Distance calculations are
based on voltage and current waveforms recorded by the device in response to a detected
fault event, and line impedance parameters provided by the user. Impedance calculations
use synchronous voltage and current phasors or sequence components depending on the
fault location method and the type of a line fault.
Fault locator features:
 Immediate on-line distance to fault and fault impedance information
 Onboard storing of fault distance information that is available for reviewing at
any time
 Use on 6 kV to 220 kV overhead power lines
 Single-ended and two-ended fault location methods
 Support for single-circuit and double-circuit (parallel) lines and lines with a
transformer branch
 Support for non-homogeneous (multi-segment) lines with non-uniform
impedance distribution along the line (single-circuit lines only)

1.2 Off-line Fault Location

As an alternative approach, the supplemental PAS software offers a stand-alone fault locator
that can perform fault distance calculations based on voltage and current waveforms
retrieved from PM180 devices. It features same options as the PM180 onboard fault locator.

1.3 Single-ended Fault Location

Single-ended fault location is provided by a single device connected to one end of a power
line. Single-ended fault location algorithms use one-point measurements and rely on the
fault impedance as it is seen from one end of the line. They are highly sensitive to power line
characteristics, which exact values are often not known, as well as to the impact of the fault
effects caused by mutual coupling and ground fault resistance.

1.4 Two-ended Fault Location

Two-ended fault distance calculations are based on fault data measured by two fault
recorders located on both sides of a power line. The devices exchange measured fault
information via the Internet, and both make distance calculations using positive or negative-
sequence quantities that negate much of the uncertain fault effects.
The two devices exchange measured voltage and current phasors accompanied by precise
timestamps to guarantee that both refer to the same event.
For inter-device communications, the devices must be connected to the Ethernet or to a
wireless cellular network. UDP port 502 is used for exchange of messages between devices.
Time synchronization of phasors is an important component in accurate distance calculations.
Using the GPS time synchronization is highly recommended and is mandatory when
communicating via a cellular network. In the event that the communications is provided via
the fast Ethernet, guarantied that the message propagation time along the network is stable,
the precise clock synchronization is not required as the devices are able to automatically
synchronize their local time with the remote device clock via the network.
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