IEEE 1129:2014 pdf free download – IEEE Guide for Online Monitoring of Large Synchronous Generators(10 MVA and Above)
4.1 Stator frame
Typically, stator frames for machines within the scope of this standard are made of fabricated stecl. Thereare significant structural differences in the design and construction of frames for cylindrical-rotor versus salient-pole generators. There are also major differences in the design and construction of frames forhorizontal versus vertical machines.In the case of horizontal machines with cylindrical rotors, two majortypes of frames exist: one in which the core is permanently attached to the frame, called an integral frame,and another in which the core is constructed in a fabricated steel cage that itself is inserted into the frame.The cage supporting the core can be also considered part of the frame. Also, in many air-cooled machines the core is mainly supported-attached to the bedplate while the enclosure is designed primarily to containand control the flow of air.
In all gencrators, the main purpose of the frame is to provide support to the core, as well as to anchor themachine, by transmitting stator tangential torques to the foundation. In most generators,the frame alsoincludes an outer cover (the casing) to contain the cooling air or hydrogen.Air or hydrogen coolers areinserted inside or supported above, below, or at the sides of the frame. Some air-cooled machines do nothave heat-exchangers.
4.1.1 Frame vibrations
Problem Description: There are number of problems that can develop with the frame, such as cracks,distortion，loose footing,and excessive vibration.Frame issues are normally detected during periodicmaintenance inspections.In most cases, the frame is the less problematic component of a large generator,thus monitoring is unusual. In those cases where monitoring is applied, the parameter tracked is vibration.Vibration of the frame can be the result of a problem intrinsic to the frame (such as cracks, distortion, orloose footing), but in most cases it is due to other component problems.
Instrumentation: Frame vibration is tracked with the help of vibration probes mounted on the frame insideor outside the casing in one location or several locations. Triaxial probes may be used but are notnecessarily required for this application.
4.1.2 Presence of liquids
Problem Description:Free liquids (water andor oil) inside the casing or in the winding itself are the result
These free liquids havec the potential to challe nycarog ein scarist, and from inner-cooled coils (by oil or water).the coils and create corrosion on metal components loosen ystatore wnsula on of thle core laminations andblock the flow of cooling gas (by oil andor water). Loss of liquids can also cause loss of lubrication,cooling, and the failure of hydrogen seals. Furthermore, in machines with open enclosures oil can combincwith dust from the surrounding environment and clog cooling air passages.
lnstrumentation: One of the methods for monitoring for the presence of free liquids in the machine is bycollecting them at the bottom of the casing and removing them from the machine via drain lines. Thescdrain lines may be fitted with sight glasses andor detector circuits generating alarms in the presence ofliquids. The sight glass can be considered a monitoring function as defined in Clause 3.