Description
Features − Negative sequence overcurrent relays are used to detectunbalanced load on a generator which may cause excessive rotor heating. The relay is also used to detect unbalanced load currents in motors. − The relay can also be used in the other applicationssuch as: − Unsymmetrical load which increase the negative sequence current. − Phase interruptions e.g. a broken conductor. − Failure on one or two poles of a breaker or disconnectswitch at opening and closing − Earth-fault detection in solidly earthed system. − The relay has I-Start, I-Alarm, I-Trip andBlocking functions. − Three current ranges: Ir = 1 A, Ir = 2 A and Ir = 5 A − Set range I-Start 4-40% of Ib (machine current) with inversecharacteristict = K x (Ib /I-)2;K= 0-100 seconds ordefinite time = 0-100 minutes. − Set range I- Alarm 3-30% of Ib (machine current) with defi-nite time = 0-100 seconds. − Thermal memory for block and trip function with the settable cooling time up to 200 minutes − Reset time I-Trip = 0-5 seconds. − Five independent output relays selectable for In Service,I-Start, I-Alarm, I-Trip, Blocking as well as Group 2 active. − Easy selectable setting of parameters through the HMI. − Trip information available via the HMI. − Two groups of setting parameters are settable and readable through the HMI. The active setting group 1 or 2 canbe selected through one of the two binary inputs. − Selectable binary inputs to block or enable I-Start, I-Alarm,I-Trip, change active group and reset of LED and timer. − Testing of the output relays and operation of binary inputscan be performed through the HMI. − Service values are available through the HMI. − Test switch, DC/DC converter and heavy duty trip relaysare available as specified options.
Negative sequence current relays are primarily applied toprotect generators and motors but also sometimes used intransmission systems to detect unbalanced conditions andfaults. The advantage of the negative sequence current overzero sequence current is that mutually coupled parallel linecurrents are not influencing the measurement and that onlythe three phase currents are used as inputs, i.e. the neutralcurrent is not needed. When a generator is connected to a balanced load the phasecurrents are equal in magnitude and are 120 degrees fromeach other. The flux produced by the stator currents rotatesynchronously with the rotor and eddy currents are not induced in the rotor parts. Unbalanced currents give rise to a negative sequence component in the stator current. The negative sequence current produces an additional flux which rotates at synchronously speedin the opposite direction of the rotor. The eddy currents whichare induced in the rotor parts will have the double networkfrequency. During such sustained conditions, the temperatureof the rotor may reaches high levels which accelerate theageing of the insulation and cause mechanical stress on therotating components.
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.
【 Disclaimer 】 We sell new products and discontinued products, independent channels to buy such special products. Guizhou Yuanmiao Automation Equipment Co., Ltd. is not an authorized distributor, dealer or representative of the products featured on this website. All product names/product images, trademarks, brands and microlabels used on this Website are the property of their respective owners. Descriptions, depictions or sales of products with such names/images, trademarks, brands and logos are for identification purposes only and do not imply any association or authorization with any rights holder. This article is from the official website of Guizhou Yuanmiao Automation Equipment Co., LTD. Please attach this link:http://www.ymdcs.com/ABB/
