Fault protection of tripping and closing circuit o

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Breaker tripping and closing circuit fault protection

1 breaker tripping and closing circuit fault analysis

at present, most of the 35kV substations subordinate to Shaanxi local power group company have been transformed into integrated automation stations, and all new stations are also integrated automation stations. All integrated automation stations, whether 35 kV circuit breaker closing control circuit or 10kV circuit breaker closing control circuit, are equipped with closing hold circuit; Correspondingly, the trip control circuit also has a trip hold circuit

the faults caused by the closing circuit are: burning the closing coil or closing connection to meet the market demand for high-performance materials, contactor coil, closing hold relay, closing contactor contact, etc. In serious cases, it is easy to cause loss of battery pack, tripping of battery panel output circuit breaker, damage of closing electromagnet and damage of closing mechanism. There are many reasons for the above faults, mainly:

· the transmission of circuit breaker mechanism is not flexible

· the energy storage spring does not store energy (for the circuit breaker of the spring energy storage mechanism)

· insufficient battery energy

· the closing fuse is not closed, fused or in poor contact

· contactor failure

· closing electromagnet failure

· other faults of circuit breaker mechanism

· the auxiliary normally closed contact of the circuit breaker cannot pop open

the above reasons may cause manual closing and monitoring closing, especially when automatic reclosing, the closing coil or closing contactor coil has a current of 0.4~2.2 a for a long time (10 K these advantages make it an ideal material for aircraft structure. V vacuum circuit breaker electromagnetic mechanism contactor coil has a current of about 0.4 a when closing; 35 kV SF6 circuit breaker spring energy storage mechanism has a current of 2.2 a when closing). The length of its charging time depends on the time when the closing holding circuit can disconnect the power supply. Closing coil or closing contactor coil and keeping relay charged for a long time are easy to burn out

similarly, such problems also exist in the tripping circuit

it can be seen from Figure 1 that when SHJ or lj2 is closed instantaneously during closing, HBJ will be charged until DL is disconnected due to self holding. When the closing is successful, the circuit breaker is in the closing state, and the normally closed contact DL of its auxiliary switch is naturally disconnected. When one or more of the above reasons occur at the same time, DL cannot be disconnected in time, HBJ is charged for a long time, and HC is also charged for a long time, which is easy to burn HC and HBJ coils; Because HC is charged for a long time, HC contact circuit is also charged for a long time, which is also easy to burn HC contact and closing electromagnet; When closing, the bus closing power supply ± HM provides about 100 a current, which is also easy to make the battery loss

the spring fatigue testing machine of the whole closing system should be properly grounded, and the closing is successful within 1 s under normal conditions. The closing coil and HBJ coil are also designed to allow instantaneous passage of large current. When passing large current for a long time, it is easy to burn the coil. If the circuit is designed so that the closing coil passes through a small current, the holding circuit is difficult to maintain itself. The increase of coil diameter is limited by position. Based on mature fire-resistant B1 polyurethane material technology

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