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Basically, the generator load is a gigantic magnetic braking force. In normal turbine operation, the driving force (steam or gas pressure) is equal to the braking force of the generator and the turbine-generator speed is constant. When the braking force is suddenly removed, the turbine force must also be removed before the turbine and the generator components rapidly spin out of control, potentially causing millions of dollars in damage. gas variables pogil answers Your overspeed protection system must be ready to avert this disaster.

Overspeed protection devices can be mechanical (trip weight), electrical or a combination of both. Units can have a mechanical governor or EHC controls. Regardless of the mechanism, all overspeed protective devices are designed to stop the steam or fuel from entering the turbine(s) upon an increase in normal speed. Most overspeed trip mechanisms are set to trip the unit at 110% of rated speed, but most turbine-generators are designed to temporarily operate at up to 120% of rated speed. Lower overspeed settings may be required for certain reheat units and nuclear applications.

Failure to remove the driving force (steam or combustion) can unleash torque forces which can destroy your turbine-generator. For example, a modest-sized steam turbine can have a start-up flow of 40,000 lb/hour to synchronize the generator to the grid and close the breaker. As the generator takes on load, steam flow is increased from the initial 40,000 lb/hour to a much greater flow (let’s say 2,000,000 lb/hour) and the turbine goes no faster! That additional 1,960,000 lb/hour steam flow has created torque to drive the generator.

Under a full load rejection, the generator armature reaction that opposes those additional pounds per hour of steam flow is suddenly removed. Now there is an unopposed 1,960,000 lb/hour of steam flow accelerating the turbine. We should not be concerned so much with how fast the turbine will go, because the speed will be way too much. We are more concerned with how fast the turbine-generator will accelerate and how quickly the turbine inlet steam valves will have to close. If the steam is not shut off, the turbine achieves the 120% rating value in seconds. electricity and magnetism worksheets 4th grade Seconds later, bearings are failing, blades are failing, disks are failing or being pushed into the diaphragms, generator retaining rings are failing, and the rotor is being pushed into the core.

Combustion turbine operators may feel safer because the compressor load acts as an additional brake on acceleration. However, this retarding force will only afford you a few extra seconds. Whether steam or combustion driven, your turbine-generator needs to be ready and personnel need to be ready. electricity prices per kwh 2013 There is no warning and you have so little time to act!

During the spring outage season Power Services Group was contacted by an Industrial Steam Turbine Owner in the Midwest with the intent to purchase a new diaphragm assembly (upper and lower halves). The customer was advised by the OEM that their existing diaphragm assembly was beyond economical repair. The lead time and price provided by the OEM to manufacture a new diaphragm assembly would have put the customer over budget and beyond the allotted schedule for their planned outage in progress.

After incoming inspection, our technicians executed a major weld repair of the admission and exhaust side inner and outer setback faces of both diaphragm halves. Upon completion, final dimensional inspections were performed. After thorough quality verification, the diaphragm assembly was expedited back to the customer’s facility, successfully installed, and returned to service.

PSG provided the customer an alternative, attractive solution they thought was unattainable. The diaphragm assembly was restored, instead of replaced, at much lower cost than a new diaphragm assembly. Even more importantly, extensive repairs were completed within 11 days of initial contact, versus the long lead time of new component manufacturing. PSG saved the customer significant downtime and associated lost production revenue. We are proud to have a satisfied customer we were able to help through an extremely difficult situation.

Directly measuring bearing metal temperature is the most effective way to really determine if a bearing is running hot. Bearing oil drain temperatures are still being utilized on older machines. By the time the bearing oil drain temperature has increased, the bearing may have already been compromised (wiped). wd gaster x reader PSG recommends that these older machines should have temperature probes (thermocouples or RTD’s) installed in the bearing Babbitt to properly monitor performance. A two-level alarm is recommended (not automatic trip). The first alarm should be set a few degrees above the highest temperature in the recommended normal operating range. gastroenteritis Operators should closely monitor bearing temperature after the first alarm sounds. If the temperature rises abruptly and unexpectedly, the bearing may have been compromised and immediate action needs to be taken. Gradual temperature changes which trigger the alarm may be the result of other factors but are still a concern and should be thoroughly investigated. The second alarm should be set at the maximum operating temperature of the bearing material. Operators should manually trip the unit in a controlled manner as soon as possible after this second alarm sounds and determine the cause. The critical temperatures for each of the two levels can be supplied by the manufacturer or recommended by PSG for your individual unit configuration. Different temperature ranges are recommended for Tilt Pad, Elliptical, Short Elliptical and Thrust bearings. Measuring drain oil temperature is too slow and too imprecise to effectively minimize your overall cost of maintenance. Retrofit your machine and save your bottom line.