Incremental Circuit Upgrades

MD&A Control Systems Division has more than 500 circuits installed in 57 power stations throughout the United States.

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An abbreviated list of incremental circuit upgrades available from MD&A includes:

• Back-Up Control System: Bypasses primary control circuitry to allow on-line maintenance.
• Back-Up Overspeed Trip F/V: Replaces Megacycler based OEM circuit with more stable F/V speed sensing.
• Circuit Extender Card: Two piece extender with test points allows for enhanced analog and logic troubleshooting.
• Control Panel Replacement: Completely isolated from cabinet power for increased reliability. All digital metering and set-point controls.
• Digital Admission Transfer Circuit: Replaces electro-mechanical FA/PA motor drive, motor pulsing circuitry and associated voltage comparators.
• Digital Load Reference Circuit: Digital Load Reference Circuit Replaces OEM circuit with more stable amplification and adds decrease loading ramps.
• Digital Load Set Circuit: Replaces the electro/mechanical Load Set Motor Drive assembly.
• Digital Position Control Circuit: Replaces the Diode Function Generator valve position circuit, with a programmable digital circuit.
• Digital Set Point Circuit: Replaces any manual or motor driven set point pot.
• FA/PA Voltage Comparator: Eliminates the FA/PA transfer limit switches located in the steam valve junction boxes.
• Frequency to Voltage Converter: Direct replacement for OEM F/V's or replaces older Megacycler circuits.
• High Voltage Logic Circuit: Replaces High Voltage Mercury wetted relay boards with solid state switches.
• IC Operational Amplifier: Replaces discreet component amplifiers or OEM IC op amps and has on board spare.
• Integrated Valve Driver Circuit: Replaces SADI boards and eliminates 3KC oscillators.
• Isolated Buffer Circuit: Provides isolation for monitoring of analog signals by other plant system with a wide range of outputs.
• Linear Variable Transformer Circuit: For pilot valve and operator cylinder position sensing.
• Low Voltage Logic Circuit: Replaces Low Voltage Mercury wetted relay boards with solid state switches.
• Meter Relay Replacement: Monitors trip test functions with solid state voltage comparators eliminating troublesome meter relays.
• Stage Pressure Bias Circuit: Gives a bumpless transfer to stage pressure feedback operation during valve testing.
• Throttle Pressure Limiter Circuit: Enhances limitter operation for sliding pressure operation and locks out limit action on transmitter failure.
• Time Delay Relay Circuit: Replaces antiquated timers with solid state equivalent.
• Valve Feedback Circuit: Provides wide range adjustable feedback signal from non servo controlled valves.
• Voltage Comparator: Direct replacement for OEM circuit.
• Voltage Sensor Circuit: Replaces obsolete OEM power supply monitor circuits.

For more information on MD&A Control Systems' products and services, please call (970) 224-2223 Ext. 140 or email: amcneill@mdaturbines.com