加州 Water Authority Upgrades SCADA Network With Redundant Ring 以太网 开关

Larry Seifert, CCWA维修主管.

随着公用事业升级旧的网络，冗余环形以太网交换机越来越受欢迎. 除了以太网的简单性的好处之外, 可扩展性和维护, 这些精密的交换机在光纤或设备发生故障时，可以自动切换到备用数据路径，从而最大限度地提高可靠性.

加州中央海岸水务局(CCWA)最近用冗余环形以太网交换机升级了其160英里长的SCADA光纤通信网络. Faced with equipment and vendor support issues, it began the planning process in late 2003.

加州中央海岸水务局.

香农·斯威尼说, 主管工程师, 最初的重点是替换光纤网络中的21个旧的ModBusPlus调制解调器，该网络将可编程逻辑控制器(plc)连接到其主要网络, a "PremNet 500" self-healing ring fiber optic backbone transport system manufactured by Milgo.

"About two or three years ago we began experiencing fiber modem failures," Shannon said. “沙巴体育足球开户有一些备用的, 但沙巴体育足球开户也开始寻找新的调制解调器，因为这些调制解调器故障暂时中断了一小部分的系统."

然后, 另一个问题出现在NextiraOne宣布将在不久的将来停止支持PremNet系统时(NextiraOne在2001年收购了Milgo)。. 90年代中期安装的, the PremNet System functioned effectively; however, CCWA关切的是，一旦目前的备件库存用完，今后的设备故障可能会严重影响其网络.

The timing of this announcement actually turned out to be a positive.

"Instead of looking only at solving the modem failures, 沙巴体育足球开户还考虑用更快的光纤通信系统取代PremNet [10Mbps],”她解释说. "This analysis led us to ask whether we needed to have all of these separate networks. 沙巴体育足球开户还认真研究了如何提高网络性能，并保持它的成本效益."

The TC3720 Redundant Ring Switch supports temperature ranges from -40°C to 80°C.

多余的环开关

为了满足这些要求, CCWA安装了Irvine 沙巴体育足球开户沙巴体育足球开户生产的冗余环形以太网交换机, 加州. 具体地说, 22 Model TC3720 10/100 开关 replaced the existing 28 fiber modems and 9 PremNet nodes.

The TC3720 Redundant Switch features a switchover time of less than 250 msec. and supports an extreme temperature range of -40°C to 80°C. It provided two 纤维 and Six 10/100M copper ports. CCWA可以监控光纤环, 警报条件, and fault locations for local and remote units with a web browser. 如果有纤维断裂 remote unit, the local master ALAM LED will flash and the Dry Contact will close. 通过在“监控PC”中查看“环状态”，可以准确定位故障的具体位置.

安装

安装很顺利, 但香农承认，尽管成功地进行了各种安装前测试，“沙巴体育足球开户还是很担心”. “一开始，一想到开关要放置满柜子的设备，就令人望而生畏." As an added precaution, the Premnet System remained intact as a backup.

Larry Seifert, Maintenance Superintendent, oversaw the installation.

拉里说:“基本上，沙巴体育足球开户把tc3720从盒子里拿出来，对它们进行配置……然后把它们塞进去。.

"We did have to do some minor network configuration. 实际上，将PLC接口[从ModBus]转换到以太网是最困难的方面.

“沙巴体育足球开户还测试了冗余切换到二次光纤环的能力，它工作得完美无缺."

Close-up of PremNet5000 chassis which was replaced by a Redundant Ring 以太网 Switch.

网络性能

The improvement in network performance was noticeable. 例如, 水处理厂的计算机系统用户评论说，他们在上传文件时没有遇到延迟，而在旧系统中只有零星的延迟.

Larry估计，新交换机提供的吞吐量至少为40Mbps，而旧系统的吞吐量约为4mbps. 香农指出，新网络 is "much cleaner and simpler" than the previous one. “通过限制独立网络的数量, we were able to flatten out and basically simplify the overall network," 她说.

以太网电话填充剂

The new 开关 also simplified adding telephone service via the CCWA network. This was accomplished by using 以太网 Telephone Extenders, Model TC1910s, also from TC 通信.

The 以太网电话填充剂 had two purposes: one, 他们在水处理厂和行政办公室之间提供了备用紧急电话连接, 距离超过100英里. (例如, 在最近的一次地震中，这两个重要地点之间的常规电话服务中断。.

Two, the TC1910s added telephone links between designated remote sites (e.g. Tank Site 2) and the Administration Building in Buellton. They can also be used to dial outside the 以太网 Network when connected to an analog PBX.

CCWA网络

CCWA主要的SCADA通信网络沿着山东附近的水处理厂之间130英里的管道安装, CA, and the 圣诞老人Ynez Pumping Facility in 圣诞老人Ynez, CA. The longest distance between the 22 以太网 开关 is about 38 miles (see diagram).

The network is comprised of twelve strands of single mode duplex fiber optic cable. Multimode fiber is used for shorter runs on the sub-networks. 目前, PremNet系统使用8股光纤，冗余以太网交换机使用4股光纤.

The SCADA software system monitors the PLCs located at the various pumping stations, 坦克, 阀门等. 网站在网络. The PLCs connect to a variety of critical telemetry equipment such as flow meters, 阀控制, 水位传感器, 沙巴体育足球报警和泵的启动和停止.

注:值得注意的是，每年在水处理厂附近发生的大量地震都采取了特别的预防措施来弥补. 在管道穿过圣安德烈亚斯断层的地方，已经安装了18个地面耦合器来缓冲地震的影响. 除了, 光纤电缆有额外的线圈，以增加弹性，并防止在地震相关应力或冲击的情况下破裂.

以太网电话分机(型号tc1910)在行政大楼和水处理厂之间提供各种维护电话链路和紧急电话服务, 距离超过100英里.

未来的计划

Future network plans could include IP video cameras, according to Shannon.

“沙巴体育足球开户正在认真考虑在偏远地区安装IP摄像头，以进行一般的安全监控,”她说. The cameras under consideration would be activated 通过预先指定的事件或运动参数.

它们还包括磁盘存储容量. 作为一个结果, 这些类型的IP摄像机需要最小的带宽，是理想的100mbps以太网网络.

CCWA管道

The CCWA is responsible for treating and delivering reliable, 向圣路易斯奥比斯波县和圣巴巴拉县的项目参与者提供优质补充水. 参加者包括圣巴巴拉市, Carpinteria, 圣玛丽亚, 范登堡空军基地, 曼, Buellton, Solvang, 圣诞老人Ynez, 奥克特和瓜达卢佩圣母.

Designated the Coastal Branch Phase II pipeline, it began operation in 1997. 它的水源来自加州供水工程的一个引水渠，该引水渠起源于萨克拉门托-圣华金三角洲，在其位于波洛尼奥山口的水处理厂每天处理多达4300万加仑的水. After undergoing a process to remove the disinfectant at the 圣诞老人Ynez Pumping Facility, the excess water that is not distributed is then pumped into Lake Cachuma.