|
In today's information intensive world, Utility Relay and Communication Engineers need access to the increased data available from modern protective relays, RTUs and other substation equipment. The need to integrate and reliably communicate this information efficiently between locations is becoming increasingly important. The Pulsar business unit of AMETEK offers FOCUS, designed specifically for the increasing needs of the power industry.
FOCUS provides a flexible package for multiplexing virtually any type of signal or data directly onto fiber optic cables. Electrical interfaces to higher order multiplexing schemes such as M13, SDH or SONET (OC-3, OC-12, etc.) are also available. FOCUS drop and insert networks will work effectively with any combination of mixed communication links such as 1300/1550 nm single-mode fiber optics, SDH, SONET and digital microwave. This allows easy integration into existing systems. The drop and insert feature also improves channel conservation and eliminates the need for back-to-back channel banks. FOCUS offers four T1/E1 ports in one chassis, which can be fiber optic, electrical or a combination of both. Both features enhance the application of FOCUS for looped networks and loops with spurs.
FOCUS uses byte-interleaved time division multiplexing at a standard T1/E1, 1.544/2.048 Mbps rate, in ESF/HDB3 format; this assures compatibility with standard communications networks and DS1/DS0 test equipment. The FOCUS T1/E1 system can multiplex up to 24/30 channels into its data stream. Each of these channels may be used for transmission of analog or digital data, pilot wire differential data, or other relay information required by POTT, PUTT, blocking, unblocking or DITT systems.
Increasing demand for real time information from the substation has created a need for "intelligent" communication systems that facilitate setup, modification and data acquisition. The FOCUS system is designed to meet these demands by being 100% software configurable without the use of DIP switches or jumpers.
FOCUS Configuration Software
The PC-based FOCUS Configuration Software (FCS) supplied with every system provides a Windows® interface for all system and channel settings. Some of these include time-slot mapping, local and remote loopbacks, system status, alarms, targets, data stream errors and channel module settings including trip delays, signal gain, security levels. The standard Remote Node Configuration (RNC) package enables execution of all FCS commands over the FOCUS network to all remote terminals. Remote communication is as simple as connecting a PC to any FOCUS node and selecting the desired remote node from a "pull-down" menu.
Once communication is established, commands are executed as if the user were standing in front of the remote chassis. RNC saves valuable time and money since all modifications and data collection can be accomplished without having to visit every substation individually.
Four-fiber hot-standby ring
FOCUS offers several network management options for the protection of critical communication channels in the event of a link or node failure. The four-fiber hot-standby ring option utilizes two pairs of fibers between adjacent nodes in the ring. One of the fiber pairs is used as the main communication path, and the other pair is used as a hot standby or redundant path which is shared by all nodes in the loop. A break in the primary path between two nodes initiates rerouting of all 24/30 channels through the standby fibers. The rerouted signal travels in the opposite direction around the ring to arrive at the node on the opposite side of the break. This procedure reliably reconnects all channels affected by the break.
The signals are automatically returned to the main fibers when the normal path has been restored. Unlike traditional path-switched schemes, the four-fiber hot-standby ring allows the user to make use of the full T1/E1 bandwidth between each adjacent station. (All 24/30 time slots between any two locations can be reused any number of times around the loop.)
The system provides fast hardware-based service restoration with complete reconfiguration typically in less than 25ms. High reliability is maintained by continuous monitoring of the standby fibers to insure availability in the event of a fiber link or node failure.
Alternate Path Mode
The Alternate Path Mode (APM) software allows for any channel module, in a loop configured network, to link to its complement should the primary path become non-functional. All required rerouting is performed automatically without any user intervention or initial setup for designating rerouted channels.
All 24/30 channels in the T1/E1 stream are available to the user and may be used only once within the loop. When a link or node fails, adjacent nodes detect the failure and send a message in the opposite direction around the ring. The message specifies which channels have been affected by the failure.
Each node containing an affected channel drop reverses the transmit direction for that channel. Nodes located between the affected channel drop nodes are converted to pass-throughs for these channels. This flip-flop procedure quickly reconnects all broken channels in the opposite direction around the loop. When the primary path is re-established, a complementary message is sent causing each node to return to its original setting. This typically happens in 125 to 250ms.
|
