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Control Systems

Obermeyer spillway gates and inflatable dams are supplied with control systems in accordance with customer requirements. Each control system includes a controlled source of compressed air and a means for controlled venting of air from the air bladders. All automatic systems also include provision for local manual control. With the exception of solar powered systems, each system includes an air compressor, a receiver tank, and various control valves. Most systems, especially those subject to freezing conditions, include air dryers.

Programmable Controllers
In many applications it is desirable to control Obermeyer spillway gates with a programmable controller. A programmable controller is ideal for complex control schemes such as maintaining precise environmentally mandated spillway flows under varying head pond elevations at hydroelectric peaking plants. Existing programmable controllers at numerous hydroelectric plants can be used to control Obermeyer spillway gates, thus reducing the overall cost of the gate installation. Conversely, at new projects, an Obermeyer supplied programmable controller can also serve other control requirements not related to the spillway gates. Programmable controller based systems can be provided with pneumatic water level controllers as a mechanical backup.

Solar Powered Controls
Obermeyer Spillway gates can be supplied with solar powered compressors and control systems. Obermeyer spillway gates are well suited to solar powered operation because no large electric motors are required even on quite large gate installations. Solar powered systems normally use 12 volt solar panels, battery and compressor. A programmable controller with optional remote control operates the compressor or vent valves in accordance with water level readings or remote control signals.

Pneumatic Water Level Control
One of the available control systems uses an all pneumatic water level controller to automatically regulate air bladder pressure in inverse proportion to upstream water level. This system requires no electrical power to accurately maintain a constant upstream pool elevation over a full range of gate positions and spillway flow rates. This controller is ideally suited to hydroelectric projects where a turbine load rejection is often associated with loss of electrical power. This control system is also ideal for safety critical flood control projects where flood conditions and extended loss of electrical power often occur simultaneously. Upstream water level is sensed by a bubbler line. The minute amount of air required for the bubbler system is supplied from the air receiver with the air stored within the air bladders connected as a backup supply.

Safety Critical Applications
For relatively small gate installations on large rivers, it is usual to operate all of the air bladders on the same pipe or pressure manifold. For large gate installations on narrow populated river channels, check valves are used on each air bladder to insure that damage to any one air bladder cannot release air from any of the other air bladders. This feature is an important safety advantage of Obermeyer spillway gates over rubber dams.

Flow Measurement and Control
Obermeyer Spillway gates respond to changes in headwater elevation and internal air pressure in a precise and repeatable manner. For any particular gate installation, the flow rate and gate crest elevation can be calculated as a function of the measured upstream pond elevation and the controlled air bladder pressure. Flow rates for submerged installations, i.e., installations with high tail water, can be calculated as a function of upstream and downstream levels and air bladder pressure.

Independent Operation of Groups of Gates
At many projects it is desirable to control various sections of the spillway independently. This can be accomplished by simply providing separate pipes to each independent section. No intermediate piers are required. Applications for this scheme include:

  • Releasing floating debris from near a power plant intake
  • Concentrating flows to discharge upstream sediment
  • Minimizing tail water elevation by releasing excess flow away from the power plant
  • Providing fish way attraction water in the precise amounts and locations needed
  • Diverting flows to allow inspection access to the raised portion of a gate system

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