1, the main difference is:
The transformer differential protection device consists of a single chip microcomputer with high integration and no bus separation, a high-precision current-voltage transformer, an export intermediate relay with high insulation strength, a high-reliability switching power supply module and other components. This device is mainly used to protect transformer equipment.
Differential quick-break protection is to overcome the problem of long action time limit of overcurrent protection device near power supply end, and protect the line by improving setting value and limiting action range.
2, the difference in principle:
When some short-circuit faults occur in this area, short-circuit currents with the same size and different phases will be generated in the secondary circuit of CT of current transformers on each side of the transformer.
When the vector sum of these short-circuit currents (that is, differential current) reaches a certain value, the protection of circuit breakers on each side of the transformer will trip.
Differential quick-break protection, in order to prevent the high-order harmonics generated when the current transformer is saturated at high short-circuit current level from increasing greatly.
When the short-circuit current reaches 4 10 times the rated current, the differential protection will refuse to act.
3. Functional differences
Transformer differential protection device should have differential quick-break protection and compound ratio differential protection with or without second harmonic braking, which can be used for three-side differential current input (three-winding transformer) at most.
It has a complete and powerful acquisition function for voltage and current analog and switching value of primary equipment, and is equipped with standard RS485 and industrial CAN communication ports. Through reasonable configuration, it has realized protection and measurement and control functions such as three-ring main transformer differential protection, two-ring main transformer differential protection, two-ring distribution transformer differential protection and non-electric quantity protection.
It is mainly used to protect various phase-to-phase short-circuit faults in the windings of double-winding or three-winding transformers and their outgoing lines, and can also be used to protect single-phase turn-to-turn short-circuit faults of transformers.
Current transformers are installed on both sides of the winding transformer, and the secondary side of the winding transformer is connected by circulating current method, that is, if the terminals of the current transformers on both sides face the bus side, the terminals of the same level are connected, and a current relay is connected in parallel between the two connections.
Extended data:
Advantages of transformer differential protection device:
1, each protection function is relatively independent, and the protection setting value, time limit, locking condition and protection switching can be set and configured independently;
2. The realization of protection function does not depend on communication network, which meets the reliability requirements of power system for protection;
3. Support manual switching of multiple sets of protection settings;
4. Closely cooperate with the functions of event recording, fault recording and communication to make the application of relay protection technology reach a new level;
5, set protection, measurement, monitoring, control, man-machine interface, communication and other functions in one; It replaces all kinds of conventional relays and measuring instruments, saving a lot of installation space and control cables.
6. It adopts 32-bit digital signal processor (DSP), which has advanced kernel structure, high-speed calculation ability and real-time signal processing ability.
7. Support conventional RS485 bus and DeviceNet(CAN) field bus communication. CAN bus has error correction mechanisms such as automatic retransmission of fault frames and automatic disconnection of fault nodes, which ensures the real-time and reliability of information transmission. Maximum speed 1Mbps, maximum distance 10km. A bus can connect at most 1 10 devices.
8. Fully enclosed metal cabinet, ultra-thin design, clear height of only 100mm, which can be applied to any cabinet type, especially the ring network cabinet.
Surface mount technology, important devices (such as chips, power modules, transformers, relays, capacitors, LCD screens, terminals, etc. ) are mature products of well-known foreign companies, and the average time between failures is 100000 hours.
9, perfect self-checking ability, found that the abnormal equipment can automatically alarm; With self-protection ability, it can effectively prevent the permanent damage of equipment caused by wiring error or abnormal operation; Maintenance-free design, no need to adjust the sampling accuracy on site, and the measurement accuracy will not be improved due to environmental changes and long-term operation.
10, an international universal input power supply module, is compatible with 85 ~ 264 V AC or DC power supply, and has excellent performance in power supply drop and voltage abrupt change.
The circuit breaker operation loop has hardware anti-jump locking module which is common for AC and DC, and the current of the opening/closing operation loop does not affect the normal work of the module. 1 1 and the enhanced function of circuit breaker operation management can be applied to substations and distribution stations with various operation modes.
12, the switch input supports direct tripping or alarm, and is used for important protection such as gas and temperature or interlock tripping. Using the technology of setting displacement confirmation time window, the jitter and electromagnetic interference of switch contacts are effectively eliminated, and the accuracy of remote communication is guaranteed to reach 100%.
13, the man-machine interface meets the requirements of ergonomics design, backlight graphic LCD, menu design, full Chinese display and reasonable screen protection control. The display contents include measurement data, switch state, real-time waveform, event record, fault record, protection setting value and system parameters.
14, with event recording function, can record all events related to the safe operation of power system, with time resolution less than 1ms, and can record 100 events online, without losing power, which is convenient for analyzing fault causes and diagnosing equipment defects.
15, with fault wave recording function, can truly record the current, voltage, switch state and other information before and after the fault. The recording density is 24 o'clock every week, and the recording length is 2 weeks before the failure and 7 weeks after the failure, and the power failure is not lost.
16, with multiple sets of protection setting manual switching function.