"Stator Leak Monitoring System"
FACT SHEET GE Energy Stator Leak Monitoring System SLMS Features The Problem In generators with water cooled stator windings, water leaks can represent a serious ❚ Easy on-line installation problem. ❚ 0 to 250 Cubic Feet/Day H2 leak range Not only can leaking water damage the stator’s insulation, it can also damage retaining rings and ultimately cause catastrophic failure of the stator winding. In ❚ Pre-assembled and packaged design addition, it has been shown that the presence of stator winding leaks can lead to ❚ Convenient data trending and storage copper corrosion within the stator winding as a result of fluctuating oxygen levels. ❚ Variable alarm level and remote Past methods of on-line leak detection have typically been cumbersome and notification inaccurate. As a result, they’re often performed infrequently or not at all. Even ❚ System interface with most routine, periodic on-line testing runs the risk of leaks going undetected for several monitoring systems days and their inaccuracy makes all but the largest leaks undetectable. ❚ Maintains proper water oxygen content The GE Solution ❚ 0 to 10 PPM oxygen level range GE’s Stator Leak Monitoring System (SLMS) can significantly reduce the risk posed by water leaks to your generator by both detecting water leaks in the stator winding ❚ Recording of hourly CFD and O2 and by maintaining the cooling water’s oxygen content – reducing the risk of copper readings for up to 88 months corrosion. The GE SLMS is a continuous, on-line monitoring system designed to measure hydrogen in the stator cooling water system on vented water systems. The SLMS is a unique package of instruments that measure gas flow and analyze hydrogen content in a harsh environment. Its data acquisition system allows storage and trending of the data as well as a variable alarm set point. The SLMS package also includes a design modification to maintain the proper oxygen content in the cooling water. The standard SLMS provides a screen and operator control to view current sensor outputs, leak rate, oxygen level and historical data. This data can be transferred by ethernet, ModBus or by the flashcard for leakage trending, printing and long-term storage of data. A visual or audible alarm can also be connected to the module to trigger at a variable setpoint. A 4-20mA output signal of the hydrogen leakage rate can be sent to the plants control room PC or DCS. SLMS Operation The GE Stator Leak Monitoring System is able to detect stator water leaks by moni- RDC27633-02-01 toring the amount of hydrogen gas venting from the stator cooling water system. In a leak free winding, the hydrogen is present in the water system in only trace amounts due to diffusion through the teflon water hoses inside the hydrogen pressurized gen- erator. After a leak develops, hydrogen, which is at a higher pressure than the cool- ing water, can pass through the leak into the water system. The hydrogen gas leaves the water storage tank and passes out the YTV vent. The SLMS measures the gas flow rate and hydrogen concentration to determine the hydrogen leakage rate which is directly related to the presence of stator winding leaks. FACT SHEET Small stator leaks (less than 1 CFD) can lead to stator damage over an extended Benefits period of time. These cannot be detected on-line and should be tested routinely. ❚ Continuous on-line monitoring lowers The proper cooling water oxygen content is maintained by modifying the stator water risk of stator damage cooling system (SWCS) to introduce a steady fresh air flow through the water storage ❚ Enhanced leak detection sensitivity tank. Without this modification, stator winding leaks can reduce water oxygen levels ❚ Aids outage planning and cause copper corrosion of the stator winding. ❚ Helps reduce the risk of: SLMS Installation — Stator insulation damage Installation of the hydrogen leak detector system is accomplished in five steps: — Rectifier grounds — Line blockages 1. Modification of the SWCS drain 2. Nitrogen gas purge of the SWCS ❚ Minimizes stator bar copper corrosion 3. Modification of the SWCS pressure gauge assembly ❚ Minimizes resin bed damage 4. Mounting of the SLMS cabinet assembly 5. Modification of stator water cooling piping for oxygen sensor All necessary components needed to connect the SLMS to the stator water cooling system are supplied in the SLMS shipping container. The purchaser must supply an instrument air supply line. The GE SLMS is a pre-assembled and packaged system designed for easy installation with the generator in or out of operation. Installation may be accomplished in approximately one shift. GE installation services are available. Annual Maintenance ❚ Gas analyzer calibration ❚ Replace air filter elements at Generator Minor Outages PLANT VENT MONITORING GAS SYSTEM SWCS WATER ALARM SAMPLE OUT RETURN WATER COOLED STATOR SAMPLE IN POWER IN (110V AC) 6 CFD WATER STORAGE PLANT AIR SLMS TANK SUPPLY SYSTEM 6.5-CPM@ PUMP COOLING WATER 100 PSI DRAIN AIR INJECTION Contact For more information, contact: GE Energy 4200 Wildwood Parkway Atlanta, GA 30039 Phone: 1-800-4GE-FAST g www.gepower.com GEA-12303C (03/04)