IEEE Std 125:2007 pdf free download

IEEE Std 125:2007 pdf free download.IEEE Recommended Practice for Preparation of Equipment
Specifications for Speed-Governing of Hydraulic Turbines Intended to Drive Electric Generators.
5.2.5 Control actuator limit
The governor-control system should provide a means of limiting the maximum allowable positon of the turbine-control actuators, which should be adjustable th,m ,cro to full control actuator stroke. The control actuator limit should also be adjustable from a remote location. The provision of an adjustable minimum control actuator position limit may also be specified. The minimum control actuator position limit may be actisated or dc-activated tinder certain specified operating conditions such as oserspeed. operating with the unit circuit breaker open or while in synchronous condenser mode.
5.2.6 Control actuator velocIty or time adjustment
A control actuator velocity adjustment should be provided. Iloth the maximum opening and closing velocities of the turbine-control actuator should be independently adjustable. Typically, these maximum velocities arc expressed in control actuator full stroke operating times. The method of operation should be such that operation of any control. automatic device, or auxiliary device should be able to mose the turbine- control actuator at a velocity no greater than that set by these adjustments. The method of adjustment should be specified and should be secure, thereby minimizing the chance of accidental misadjustmcni Typical methods include adjustable distributing valve stop nuts, flow restricting orifices and flow control valves.
The opening and closing travel times should be specified and arc normally dictated by the permissible water-hammer ciTed in the water conduit and the permissible ovctspeed following load rejection. The closing time may also be dictated by the possibility of draft tube water column separation. The opening time may also be dictated by the possibility of swge tank (or surge shaft) air entrainment.
5.2.7 Control actuator posItion feedback
Control actuator position feedback is a basic requirement of a speed-governing system. The position feedback system is used to transmit the position of the turbine-control actuators to the governor-control system. The response lime of the position feedback system should be compatible with the governor perfonnance requirements as specified in Clause 6. The accuracy and resolution of the position feedback system should be specified and shotild be guaranteed over the operating temperature range specified in 5.11.1. Values of 0.1% for accuracy and 0.02% for resolution have been found through experience to provide acceptable performance.
The position feedback system should be designed such that any failure in the mechanism will cause the turbine-control actuators to respond in the manner specified (for example, force the turbine-control device to fully close).
5.2.8 Speed-sensing source
Speed sensing is a basic requirement of a speed-governing system. The range and response time of the speed-sensing source should be compatible with the governor pcrthnnancc requirements (as specified in Clause 6) and as required for thc adjustment range of the speed switches. The accuracy and resolution of the speed-sensing source should be specified and should be guaranteed over the operating temperature range specified in 5.11.1. Values of 0.03% for accuracy and 0.003% for resolution have been found through experience to provide acceptable pertbrmance.