Description
Features − Micro-processor based time directional current relay/protection with continuous settings for operate valuesand time delays. − RXPPK 2H is used to detect reverse power or low forward power to prevent damage of the prime mover. − Setting range Ia = 0,3 - 15 % of rated current. − Two variants, with wide setting ranges. - Scale constant Is = 0,1, 0,4, 0,7, 1,0 A or Is = 0,5, 2,0, 3,5, 5,0 A − Two different definite time delay stages. − Trip t1 = 0 - 4 s or Trip t2 = 0 - 30 s − Trip t2 function is supported with a stand by time-holdfunction, with the settings 0 or 5 s. When a Start Is hasoccurred, the t2 timer will not reset until the hold timehas expired, regardless if the Start Is has been reset. − Block functions: – − Undervoltage block: blocking all the functions if thevoltage is less than 40 V − Undercurrent block: blocking all the functions if the current is less than 0,25 % of the rated current
The purpose of the reverse power relay is basically to preventdamage of the prime mover (turbine or motor) upon a reversepower condition. If the driving torque becomes less than thetotal losses in the generator and the prime mover, the generator starts to work as a synchronous compensator, takingnecessary active power from the network. In case of steam turbines, a reduction of the steam flow reduces the cooling effect of the turbines blades and overheating may occur. Hydro turbines of the Kaplan type and bulbtype may also be damaged due to the fact that the turbineblade surf on the water and set up an axial pressure on thebearing. Diesel engines may be damaged due to insufficientlubrication. These table values apply to the case when the power input tothe prime mover is completely cut off. Thus, in the case whenthe total power losses of a unit are covered partly by theprime mover and partly by electrical power from the system,the actual power drawn by a generator, during certain motoring conditions, may be much less than the above percentagevalues. The generator currents remains balanced when the machine isworking as a motor, hence, a single-pole relay is fully sufficientif the sensitivity is high. For large turbo units, an additionalrelay may be connected to a different phase in order to obtainredundancy When the generator is working as a motor, the small activecurrent to the machine may be combined with a substantialreactive current delivered by the machine. Hence, the angular error of voltage and current transformers feeding low setreverse power relays should be small.
The company focuses on DCS, PLC, robot, large servo four systems
The main products are various modules/cards, controllers, touch screens, servo drivers Company advantage: Supply imported original products, professional production of spare parts One year warranty, fast delivery time, complete supply !！！ ① 24 hours email response (12 hours); ② For shipment outside Asia, please contact the seller.
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