Vaccum pumps in a thermal power plant.

Vaccum pumps is one area without which a thermal power plant will not be working. Vaccum pumps are used to remove the air from the condenser and provide a vaccum path for the steam to the condenser. Vaccum pumps suction is connected directly to the condenser.

During unit light up before admitting the seal steam vaccum pumps will be on and then the seal steam will be admitted.  Seal steam and vaccum pumps both ensures vaccum is maintained in the condenser. If seal steam is not provided air will be moving into the system through the shaft seal thereby effecting the condenser vaccum.

The vaccum pumps consists mainly of inlet butterfly valve, pump and a separator tank.
When the vacuum pump is on the inlet butterfly valve gets open and is connected to condenser. Now the pump will suck the air from the condenser and release it to the atmosphere through the separator tank.

The butterfly valve is the heart of the vaccum pumps as in any thermal power plant a vaccum pumped up will always be in spare along with running once. The spare vaccum pumps butterfly valve must be perfectly closed, if not since the pump is not on the air will ingress into the condenser through the separator tank via butterfly valve.

Turbovisionary parameters for steam turbines

Turbovisionary parameters are indeed the heart of the turbine. It explains the turbines vibrations at various bearings, shaft vibrations, axial shift , casing expansions, shaft expansions and differential expansions. With the help of these parameters the turbine health can and performance can be read.

Along with the physical equipment there will be a separate system to analyse the outputs from these devices and know how the turbine is rotating or are there any glitches. Etc...

Shaft vibrations also contains the bearing vibration as the shaft sensor is placed on the bearing.  Shaft vibrations uses the principle of Eddy currents.

tstransco AE electronics Preparation

Notification for tstransco Telecom exam is out and there will be lots of doubt about what to study and how to score more. First topic and scoring but most people forget is the general awareness topic, it covers Telangana related topics history geography and current scenario, latest national affairs and English and aptitude.  This can be concentrated in last one week to make sure you will not forget at the last moment. If we go across the previous question papers there can be an idea of the general questions.

When comes to the subject point of view as the syllabus covers the entire gate syllabus. Concentrate on the topics from where questions can be asked more. As the Transco deals with transmission lines it may contain electromagentic questions, communication and signals and systems can be asked more and is the important are. The edc, analog and digital circuits a general overview may be sufficient if we go through the previous gate and ies papers we come across lots of theoretical questions which may be asked.  Maths there can be basic questions again the previous gate papers questions can be more than sufficient. Major concentration area can be electromagnetics, communication, signals and systems.

Primary water and cold gas temperature control

Primary water and cold gas temperature are two important parameters to cool the stator windings and the rotor of the generator respectively. The primary water flows through the hollow stator windings of the generator thereby absorbing the heat from the stator windings. This primary water is then cooled using the DM water through the plate heat exchangers which are used for cooling the Primary water. The cooling of the primary water depends upon the primary water temperature control valve whose setpoint is some constant value above the setpoint of the cold gas temperature control valve


The cold gas or the hydrogen gas is used to cool the generator rotor the hydrogen gas is cooled again with the DM water from various coolers. The cold gas temperature control valve set point is some constant plus the temperature of the cold gas. 

Turbine overspeed trip or protection

In a thermal power plant turbine overspeed trip is one of the most important protection which saves the turbine to control the overspeed when the unit suddenly trips.

There are various reasons for turbine over speed such as sudden load throwoff, load rejection, boiler trip, turbine trip, generator trip. When the load throwoff and rejection happens on the grid the turbine speed tend to raise to supply the additional load requirement due to load throwoff or rejection. In this this case the load rejection relay (LSR) gets operated and drain the hydraulic oil which closes the HP and IP turbine control valves partially for sometime to control the turbine speed.

When the turbine trips sudden due to boiler trip, turbine protection trip or generator breaker open the turbine tends to get overspeed due to large steam available during this case the HP and IP emergency stop valves full close and reduce speed of the turbine.

The overspeed at which the turbine to be tripped is generally 10 percent above the normal rotating speed. There will be three types of overspeed trip. They are mechanical trip, logical trip and finally electrical first mechanical trip if it fails then goes for logical trip, if it also fails the sure tripping is the electrical trip

For mechanical trip there will be a setting at the first bearing of the turbine where a spring will get acted at overspeed and which drains the oil supply to the stop valves there by resulting in turbine trip.

At the first bearing there will be trip oil pump which is attached to a spindle and this spindle is attached to a small element which is attached to a spring. When the turbine exceeds the maximum speed then the trip oil pump will push the spindle inside, the element will then pull the spring inside which is connected to a limit switch, which acted as the spring moves inside draining the auxillary oil which closes the stop valves resulting in turbine trip.