Relay na Samun Kirki: Gidajen Inganci
A relay na yadda ake kira ita ce zara da take kira zabe masu iya daga abubuwa masu gaba-gaba, kamar kisan kafin kasa, kisan kasa, kisan kasa, da kuma kisan kasa. A cikin haka, ita ce zabe masu iya da ke tafiya daga birnin zabe zuwa mutane ko birnin zabe mafi. Zara da yadda ake kira ita suna da muhimmanci wajen inganta dalilin da kuma amanan zabe masu iya, domin su zai iya gano da kuma kawo gaba-gaban da za a yi ne, kuma kuma samun kasa da sauran abubuwan da za su iya kasance.
Meen ya ne Relay na Yadda Ake Kira Da Dukkana?
Daga cikin abubuwan da suka fi shahara a cikin zara da yadda ake kira ita, ana iya kiran relay na yadda ake kira da dukkana, kuma ana iya kiran relay na impedance. Relay na yadda ake kira da dukkana ke tafiya kan impedance (Z) ta ita, ta haka yana amfani da voltage (V) da current (I) daga potential transformer (PT) da current transformer (CT). Impedance an samu da yawa da V/I.
Relay na yadda ake kira da dukkana ke tafiya kan impedance da aka samu da setting value, wanda yake nufin maximum allowable impedance don aiki daidai. Idan impedance da aka samu yana da damar minuwa ta setting value, yana nufin cewa akwai gaba-gaba a cikin ita, kuma relay zai tafiya signal to circuit breaker don kawo gaba-gaban. Relay zai iya nuna parametarin gaba-gaban, kamar fault current, voltage, resistance, reactance, da kuma fault distance, a scree ni.
Fault distance wata tsari daga wurin relay zuwa wurin gaba-gaban, wanda zai iya amfani da measured impedance da line impedance per kilometer. Misali, idan measured impedance ita ce 10 ohms da line impedance per kilometer ita ce 0.4 ohms/km, yana nufin cewa fault distance ita ce 10 x 0.4 = 4 km. Neman fault distance zai taimaka wajen samun da kuma kawo gaba-gaban da kowace lokaci.
Yadda Ana Iya Amfani Da Quadrilateral Characteristic
Relay na yadda ake kira da dukkana zai iya da operational characteristics masu farko, kamar circular, mho, quadrilateral, ko polygonal. Quadrilateral characteristic ce mai fi shahara a cikin numerical relays modern saboda yana bayyana da flexibility da accuracy wajen set protection zones.
Quadrilateral characteristic ce graph na parallelogram-shaped wanda ke define protection zone ta relay. Graph ya ce da four axes: forward resistance (R F), backward resistance (R B), forward reactance (X F), da backward reactance (X B). Graph ya ce da slope angle called the relay characteristic angle (RCA), wanda yake determine shape of the parallelogram.
Quadrilateral characteristic zai iya plot da yawa da steps:
Set R F value a positive X-axis da R B value a negative X-axis.
Set X F value a positive Y-axis da X B value a negative Y-axis.
Draw a line from R F to X F with a slope of RCA.
Draw a line from R B to X B with a slope of RCA.
Complete the parallelogram by connecting R F to R B and X F to X B.
Protection zone ita ce inside the parallelogram, wanda yana nufin cewa idan measured impedance yana da damar minuwa a wannan area, relay zai trip. Quadrilateral characteristic zai iya cover four quadrants of operation:
First quadrant (R and X values are positive): Wannan quadrant yana nufin inductive load da kuma forward fault dari relay.
Second quadrant (R is negative and X is positive): Wannan quadrant yana nufin capacitive load da kuma reverse fault dari relay.
Third quadrant (R and X values are negative): Wannan quadrant yana nufin inductive load da kuma reverse fault dari relay.
Fourth quadrant (R is positive and X is negative): Wannan quadrant yana nufin capacitive load da kuma forward fault dari relay.
Wadannan Zones of Operation Ne?
Relay na yadda ake kira da dukkana zai iya da zones of operation, wanda suka define da different setting values of impedance and time delay. Zones suna design don coordinate with other relays in the system and provide backup protection for adjacent feeders.
The typical zones of operation for a distance protection relay are:
Zone 1: Wannan zone ce ta cikin 80% to 90% of the feeder length and has no time delay. It provides primary protection for faults within this zone and trips instantaneously.
Zone 2: Wannan zone ce ta cikin 100% to 120% of the feeder length and has a short time delay (usually 0.3 to 0.5 seconds). It provides backup protection for faults beyond zone 1 or in adjacent feeders.
Zone 3: Wannan zone ce ta cikin 120% to 150% of the feeder length and has a longer time delay (usually 1 to 2 seconds). It provides backup protection for faults beyond zone 2 or in remote feeders.
Some relays may also have additional zones, such as Zone 4 for load encroachment or Zone 5 for overreaching faults.
Wadannan Types of Feeder Protection Relays Ne?
Besides distance protection relays, there are other types of feeder protection relays that can be used for different applications or in combination with distance protection relays. Some examples are:
Overcurrent protection relays: These relays measure only current and trip when it exceeds a preset value. They are simple, inexpensive, and widely used for radial feeders.
Differential protection relays: These relays compare current inputs from both ends of a feeder and trip when there is an unbalance between them. They are fast, selective, and sensitive for short feeders or busbars.
Directional protection relays: These relays measure both current and voltage and determine their phase angle difference. They trip only when current flows in a specific direction relative to a voltage. They are useful for looped feeders or parallel feeders.
Arc-flash detection relays: These relays use light sensors and high-speed overcurrent detection to identify arc-flash events on feeders. They trip faster than conventional relays and improve safety for personnel.
Yadda Ake Zabi Feeder Protection Relays
The selection of feeder protection relays depends on various factors, such as:
The type, length, configuration, loading, grounding, and insulation level of feeders
The availability, accuracy, cost, maintenance, communication, and integration of relays
The coordination, selectivity, sensitivity, speed, reliability, security, and stability of protection schemes
The standards, regulations, codes, policies, and practices of power system operators
Some general guidelines for selecting feeder protection relays are:
Choose numerical relays over electromechanical or static relays for better performance, functionality, flexibility, and diagnostics
Choose distance protection relays over overcurrent or differential protection relays for long or complex feeders
Choose quadrilateral characteristics over circular or mho characteristics for more accuracy and adaptability
Choose low-energy analog sensor inputs over conventional current/voltage inputs for reduced size, weight, and safety hazards.
Choose arc-flash detection relays over conventional relays for faster tripping and personnel safety.
Conclusion
Feeder protection relays are vital devices that protect power system feeders from various types of faults. They can improve power system reliability, security, and efficiency by quickly detecting and isolating faults, preventing damage to equipment, and minimizing power outages.
One of the most common types of feeder protection relays is the distance protection relay, which measures the impedance of the feeder line by using the voltage and current inputs from the corresponding potential transformer and current transformer. It compares the measured impedance with a predefined setting value, which represents the maximum allowable impedance for normal operation. If the measured impedance is lower than the setting value, it means that there is a fault on the feeder line, and the relay will send a
