Pressure Transmitter Used in Speed Generating System and Automatic Control

Date: 2022-Mar-31


As a result of the aging and inadequate automatic control systems in old hydropower plants, the governor system, responsible for regulating power output and rotational speed of hydro turbine generator sets, frequently malfunctions, significantly impacting the normal operation and power generation of the turbines. 

The oil hydraulic system, serving as the operating system for the governor, directly influences the regulation of the hydro turbines based on its operational pressure's reliability.

Primary Issues

In older hydropower plants, the governor for hydro turbines adopts a mechanical hydraulic design, and its oil hydraulic system provides the power source for operating on-off services and automatic speed regulation of the turbines. However, this system often suffers from problems, including significant oil pressure fluctuations, frequent malfunctions, simplistic automatic control, limited protection measures, and potential risks to unit operation.

Speed Generating System and Automatic Control

Common Failures

• The limited contact capacity of the electric contact pressure gauge results in frequent starting, leading to singeing and unreliable action.

• Inadequate man-machine interface for important signal transfers and switching values, such as failure signals from the governor.

• Imbalanced equipment utilization, with the main pump operating while the spare one remains on standby for long periods. The spare pump's inefficiency can lead to further complications during emergencies.

• Incomplete protection system due to outdated electric design, poor quality pressure elements, and reduced functionality, resulting in a lack of automatic start or stop capabilities after prolonged use.


The MPM4881 pressure transmitting controller offers a solution to address the main failures occurring in outdated governors, consequently enhancing the automatic control system within the existing governor oil hydraulic device. This pressure transmitting controller has wide applications in the governor systems of various hydropower plants. Drawing on our extensive experience in product design and application in the hydropower industry, we have developed a reliable pressure transmitting controller that resolves installation, wiring, and commissioning issues, among others.

MPM4881 Pressure Transmitting Controller

In addition to the standard pressure transmitting controller, we can provide customers with comprehensive pressure monitoring and sensing solutions using pressure transmitters tailored to meet specific requirements.

transmitting controller Commissioning Site


• Reliability Assurance

1. Each control contact of our pressure transmitting controller is equipped with relays, realizing high load capacity. It can be used to replace traditional electric contact pressure gauge and solve the hidden problems of bad contact, malfunction, or failure caused by a spark.

2. The action point of the pressure transmitting controller could be adjusted and the return difference could be set according to the oil pressure of the governor system, effectively preventing the action shift (oil pump repeatedly incorrect start/stop) due to the frequent start-up or unstable oil pressure.

3. Under maximum load, the switch could act above 100,000 times, guarantees the long effectiveness and stability of the control contacts.

4. The oil hydraulic system's pressure control and automatic air make-up can be realized independently for its stability and reliability.


Impulse Governor System in Hydropower Station

• Real-time Display and Monitor

1. Various standard analog outputs can be set as per the actual situation on site.

2. The stable analog output connects with PC, LCU system, and other secondary instruments, realizing measuring data display possible after long-distance transmission.

3. Pressure transmitting controller outputs analog and switch signals which can be input to the corresponding PLC, offering an essential basis for "automatic system controls governor system" and parameters for automatic and manual adjustment of LCU system.

4. The analog output and control contacts provided by a pressure transmitting controller assists the LCU system to realize the alternative operation of main and spare pumps.

5. Together with liquid-flow annunciator (i.e.MFM500 flow switch), two pumps spare to each other, guaranteed the normal operating oil pressure of the governor system.

Impulse Governor System in Hydropower Station

(Data Collecting and Control of LCU System)

Data Collecting and Control of LCU System

(Main and Spare Pumps)

• Complete Systematic Protection

1. The accurate and stable output prevents malfunction or rejecting action after long-time use;

2. Set alarm point of accident oil pressure, providing reliable monitoring variable and automatic self-protection for governor system realizing

3. Provide reverse connection protection, overpressure protection, preventing failure and damage of governor due to the product failure;

4. Together with other mechanical pressure switches on-site, realize dual redundancy protection, preventing damage of system and equipment parts.

• Optimized installation

1. Various installation methods, applicable for different requirements;

2. Apply removable contact installation, applicable for monitoring positions with small space, and difficult to perform dismantling.

3. Apply removable terminals, easy for electrical connection;

4. Equipped with terminals protection cover or waterproof contacts, preventing dust and short circuit.

Electronic and Mechanical Products Application Site

(Electronic and Mechanical Products Application Site)

Electronic and Mechanical Products Application Site

(Installation at Working Site)

The pressure transmitting controller is suitable for governor systems, contributing to the self-protection and automatic operation of hydropower plants. Moreover, it can be employed in other equipment and auxiliary systems, such as water supply pipeline control, compressed air systems, inlet main valve control, and more, offering solutions to original control system challenges and finding broad industrial applications.

Pressure Monitoring of Air Compression System

Pressure Monitoring of Air Compression System

Pipelines Pressure Monitoring of Hydraulic Measurement System

Pipelines Pressure Monitoring of Hydraulic Measurement System

We have successfully provided pressure solutions for oil hydraulic systems in hydropower plants across the globe. If you have any requirements concerning pressure measurement and sensing, please feel free to contact us at

Common Products in the Hydropower Industry

Pressure Transmitter: MPM480/MPM489/MPM4730/MDM3051SDP

Level Transmitter: MPM4700/489W/MPM416WK

Flow Meter: MFE600

Pressure Transmitting Controller: MPM4881

Temperature transmitter: MTM4881 Temperature Transmitting Controller

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Micro Sensor GmbH
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