Detail of DL/T 995-2016

Introduction of DL/T 995-2016

Codeofchina.com is in charge of this English translation. In case of any doubt about the English translation, the Chinese original shall be considered authoritative. This standard is developed in accordance with the rules given in GB/T 1.1-2009 Directives for standardization - Part 1: Structure and drafting of standards. This standard replaces DL/T 995-2006 Testing regulations on protection and stability control equipment. In addition to editorial changes, the following main technical changes have been made with respect to DL/T 995-2006: ——The testing regulations and requirements for relay protection and stability control equipment in smart substation are added; ——The content related to state overhaul of relay protection and stability control equipment is added; ——The testing time, items, requirements, etc. of relay protection and stability control equipment in conventional substation are partially modified and improved. This standard was proposed by the Standardization Center of the China Electricity Council. This standard is under the jurisdiction of the Technical Committee on Relay Protection of Standardization Administration of Power Industry. This standard replaces DL/T 995-2006. During the process of implementing this standard, the relevant comments and recommendations, whenever necessary, can be fed back to the Standardization Center of the China Electricity Council (No.1, 2nd Lane, Baiguang Road, Beijing, 100761, China). Testing regulations on protection and stability control equipment 1 Scope This standard specifies the cycle, content and requirements of various testings for relay protection and stability control equipment in power systems as well as their secondary circuits. This standard is applicable to the installation, debugging, operation and maintenance of relay protection and stability control equipment (hereinafter referred to as “protection equipment”) for power grid enterprises, grid-connected power generation enterprises and users. 2 Normative references The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. GB/T 2900.15 Electrotechnical terminology - Transformer, instrument transformer, voltage regulator and reactor GB/T 2900.50 Electrotechnical terminology - Generation transmission and distribution of electricity - General GB/T 2900.57 Electrotechnical terminology - Generation, transmission and distribution of electricity - Operation GB/T 7261-2016 Basic testing method for relaying protection and security automatic equipment GB/T 14285-2006 Technical code for relaying protection and security automatic equipment GB/T 20840.7-2007 Instrument transformers - Part 7: Electronic voltage transformers GB/T 20840.8-2007 Instrument transformers - Part 8: Electronic current transformers GB/T 22386-2008 Common format for transient data exchange (COMTRADE) for power systems GB/T 25931-2010 Precision clock synchronization protocol for networked measurement and control systems DL/T 478-2013 General specification for relaying protection and security automatic equipment DL/T 527-2013 Technical specifications of power supply for protection and control equipment DL/T 587 Code for operating management of microprocessor-based relaying protection equipment DL/T 860 (all parts) Communication networks and systems in substations DL/T 1501-2016 Technical specifications of digital test equipment for relay protection 3 Terms and definitions For the purposes of this document, the terms and definitions given in GB/T 2900.15, GB/T 2900.50, GB/T 2900.57, GB/T 20840.7, GB/T 20840.8 and DL/T 860 as well as the following ones apply. relay protection system system that consists of relay protection equipment, merging unit, smart terminal, switch, channel, secondary circuit, etc. and implements the relay protection function 4 General 4.1 This standard gives the basic principle that the protection equipment shall follow during the testing process. The content hereof is not limited to single relay protection equipment, and also includes merging unit, smart terminal, switch, channel, secondary circuit and other equipment constituting the relay protection system. 4.2 The relay protection management, operation and maintenance units at all levels shall reasonably arrange the annual, quarterly and monthly testing plans according to the specific conditions of the local power grid and in combination with the overhaul status of the primary equipment. The relevant dispatching organizations shall support and coordinate and shall make overall arrangements. 4.3 For the testing work of protection equipment, standardized operation instruction and implementation plan shall be developed, and the testing content shall comply with this standard. 4.4 The accuracy class and technical characteristics of the testing instruments and apparatuses shall meet the requirements and shall be verified periodically. 4.5 The testing of the microprocessor-based protection equipment shall be carried out with full use of the “self-testing” function of protection equipment, focusing on the items that cannot be tested by the "self-testing" function. 4.6 For the non-outage testing work, the dual relay protection configuration and the coordination of remote and local backup protection shall be taken into account, and the principle that any electric power equipment is not allowed to operate without relay protection shall be followed. 5 Testing of relay protection and stability control equipment in conventional substation 5.1 Routine overhaul testing type and cycle 5.1.1 Routine overhaul testing type Routine overhaul testing is classified into the following three types: a) Acceptance testing of newly installed protection equipment; b) Periodic testing of protection equipment in operation (referred to as “periodic testing”); c) Supplementary testing of protection equipment in operation (referred to as “supplementary testing”). 5.1.1.1 Acceptance testing of newly installed protection equipment Acceptance testing of newly installed protection equipment shall be carried out in the following cases: a) Beginning of operation of a newly installed primary equipment; b) Input of a newly installed protection equipment on the existing primary equipment. 5.1.1.2 Periodic testing of protection equipment in operation Periodic testing is classified into the following three types: a) Full testing; b) Part-item testing; c) Tripping and closing test with the protection equipment. 5.1.1.3 Supplementary testing of protection equipment in operation Supplementary testing is classified into the following five types: a) Testing of protection equipment in operation after the major change (including software version upgrade of the protection equipment) is made or new circuit added to such equipment; b) Testing after overhaul or replacement of primary equipment; c) Testing after any abnormality is found during operation; d) Post-accident testing; e) Testing of protection equipment when it is put into operation again after power outage for one year or more. 5.1.2 Content and cycle of periodic testing 5.1.2.1 Periodic testing shall be carried out in accordance with the cycle and items specified in this standard and the content of the standardized operation instruction approved by the competent authorities at all levels. 5.1.2.2 The periodic testing cycle plan shall be formulated with comprehensive consideration of the voltage level and working condition of the equipment under its jurisdiction, and shall be carried out according to the cycle and items specified in this standard. In general, periodic testing shall be carried out as much as possible during the power outage of the primary equipment. See Tables 1 and 2 for the cycle requirements for full testing and part-item testing of 220kV or above protection equipment. Table 1 Cycle of full testing No. Equipment type Cycle of full testing (years) Description to definition scope 1 Microprocessor-based protection equipment 6 Including the AC, DC and operation circuits outside the leading-in terminal of the equipment and the auxiliary relays involved, the auxiliary contacts of the operating mechanism, the automatic switch of the DC control circuit, etc. 2 Non-microprocessor protection equipment 4 Including the AC, DC and operation circuits outside the leading-in terminal of the equipment and the auxiliary relays involved, the auxiliary contacts of the operating mechanism, the automatic switch of the DC control circuit, etc. 3 Optical fiber channel, multiplexing optical fiber or microwave connection channel specially for protection 6 Optical fiber channel and photoelectric conversion device for connecting the station-end protection equipment 4 Processing equipment (including equipment used in multiplexing with communication equipment and in conjunction with the stability control equipment and maintained by other departments) of carrier channel for the purpose of protection 6 Involving the following processing equipment: high-frequency cable, combined filter, differential network, and frequency divider Table 2 Cycle of part-item testing No. Equipment type Cycle of part-item testing (years) Description to definition scope 1 Microprocessor-based protection equipment 2~4 Including the AC, DC and operation circuits outside the leading-in terminal of the equipment and the auxiliary relays involved, the auxiliary contacts of the operating mechanism, the automatic switch of the DC control circuit, etc. 2 Non-microprocessor protection equipment 1 Including the AC, DC and operation circuits outside the leading-in terminal of the equipment and the auxiliary relays involved, the auxiliary contacts of the operating mechanism, the automatic switch of the DC control circuit, etc. 3 Optical fiber channel, multiplexing optical fiber or microwave connection channel specially for protection 2~4 Optical fiber head wiping, receiving margin testing, etc. 4 Processing equipment (including equipment used in multiplexing with communication equipment and in conjunction with the stability control equipment and maintained by other departments) of carrier channel for the purpose of protection 2~4 Transmission attenuation, receiving margin testing, etc. 5.1.2.3 When formulating the part-item testing cycle plan, the equipment operation and maintenance department may appropriately shorten the testing cycle and increase the testing items as follows according to the voltage level, manufacturing quality, operating condition, operating environment and conditions of the protection equipment: a) The first full testing shall be carried out within one year after the newly installed protection equipment is put into operation. After the second full testing of the equipment, if the equipment is found to be in poor operating condition or has exposed defects that need to be supervised, it may be considered to appropriately shorten the cycle of part-item testing and select the major testing items according to purpose. b) The 110kV microprocessor-based protection equipment should be subjected to part-item testing once every 2 to 4 years and to full testing once every 6 years; the non-microprocessor protection equipment shall be subjected to testing by making reference to the testing cycle of 220kV or above protection equipment of similar type. c) The tripping and closing test of the circuit breaker with use of the protection equipment should be carried out in combination with the overhaul of primary equipment. Supplementary testing may be carried out as necessary. 5.1.2.4 During the circuit breaker tripping and closing test for switching generator set, shedding load, cutting off line or instrument transformer and other equipment in the busbar differential protection, circuit breaker failure protection and stability control equipment, it is allowed to confirm the correctness of the wiring to the trip circuit of each circuit breaker by the conduction method. 5.1.3 Content of supplementary testing 5.1.3.1 For the testing carried out due to overhaul or replacement of the primary equipment (circuit breaker, current transformer, voltage transformer, etc.), the testing items shall be determined by the relay protection department of the operation and maintenance unit according to the nature of the equipment overhaul (replacement). 5.1.3.2 After the protection equipment in operation undergoes any major change or there is any change in the secondary circuit of the equipment, the relay protection department of the operation and maintenance unit shall test the protection equipment and also determined the testing items according to the equipment's nature of work. 5.1.3.3 In any case that the protection equipment is abnormal or is not acting correctly for any unknown cause, the relay protection department of the operation and maintenance unit shall purposely formulate specific testing items and testing sequence according to the accident situation, and shall conduct post-accident testing as soon as possible. After the testing work is completed, the report shall be issued in time, and submitted for future reference according to the equipment dispatching jurisdiction. 5.1.4 Testing management 5.1.4.1 The new type of protection equipment in trial operation shall be subjected to comprehensive inspection test and shall be reviewed by the relay protection operation management department of the power grid (provincial) company. 5.1.4.2 For the protection equipment which fails to meet the operation requirements due to poor manufacturing quality, the manufacturer shall be responsible for the solution and shall also report to the superior competent authorities. 5.1.4.3 After the protection equipment has a general problem, the manufacturer is obliged to promptly notify the operation authority and propose preventive measures. 5.2 Conditions required for the testing of conventional substation 5.2.1 Basic requirements and allocation of instruments and apparatuses 5.2.1.1 The instruments and apparatuses used for the testing of protection equipment shall be qualified upon testing and shall meet the requirements of GB/T 7261-2016. The accuracy class of the instruments and apparatuses used for the setting value testing shall not be less than 0.5. 5.2.1.2 The 220kV or above substations shall be equipped with high-frequency oscillator and selective level meter if it is necessary to debug the carrier channel. The 220kV or above substations or the concentrated control station shall be equipped with a complete set of microprocessor-based test instruments, the test lines and other tools that simultaneously output at least three phases of current and four phases of voltage. 5.2.1.3 The relay protection team shall be at least provided with: pointer voltmeter and ammeter, digital voltmeter and ammeter, clip-on ammeter, phase meter, millisecond meter, bridge, etc.; 500V, 1,000V and 2,500V insulation resistance meters; memory oscilloscope; high-frequency oscillator and selective level meter required for the testing of carrier channel, as well as non-inductive resistance, variable attenuator, etc.; complete set of microprocessor-based test instruments. It is recommended to allocate a portable oscillograph (waveform recorder) and an analog circuit breaker. If it is necessary to debug the optical fiber pilot protection channel, the instruments such as light source, optical power meter, bit-error tester, variable optical attenuator shall be allocated. 5.2.2 Preparation before testing 5.2.2.1 Before conducting on-site testing work, the testing personnel shall carefully understand the situation of the primary equipment of the tested protection equipment and its adjacent primary and secondary equipment and the details of relevant parts of the operating equipment, and accordingly formulate the technical measures ensuring safe operation of system throughout the testing work. 5.2.2.2 It is required to have the drawings consistent with the actual situation, records of the last testing, the latest setting value notice, standardized operation instruction, qualified instruments and apparatuses, spare products and parts, tools, connecting wires, etc. 5.2.2.3 The test apparatuses required to be equipped with grounding terminal is not allowed to be directly connected to the DC power supply circuit during on-site testing, to prevent the DC power supply from being grounded. 5.2.2.4 Preparation before acceptance testing of newly installed protection equipment includes: a) Understand the primary wiring of equipment, the possible operation mode after the equipment is put into operation, and the scheme of putting the equipment into operation; this scheme shall include the temporary relay protection mode at the initial stage of operation. b) Check all the drawings such as the wiring diagram (design drawing) and the compatible secondary circuit installation diagram, the cable layout, cable numbering diagram, operating mechanism diagram of circuit breaker, terminal box diagrams of current and voltage transformers, distribution box diagram of secondary circuit, as well as the principle and technical instructions of complete set of protection and stability control equipment, the operating mechanism instruction of circuit breaker, the end-of-manufacturing test reports of current and voltage transformers, etc. The above technical information shall be complete and correct. If the new equipment is debugged by the capital construction department, the relay protection acceptance personnel of the production department shall conduct acceptance inspection on the technical report after conducting acceptance inspection on complete set of technical data. c) Check that all protection equipment are installed in the correct positions on site according to the design drawings. 5.2.2.5 The setting test of the protection equipment shall be carried out according to the setting value notice provided by the relevant relay protection department. The person in charge of the work shall be familiar with the content of the setting value notice, check whether the set values are complete, and whether the transformation ratio values of the current and voltage transformers used are in line with the actual situation on the site (not limited to the verification of set functions in the setting value notice). 5.2.2.6 To conduct testing work on the operating equipment, the relay protection testing personnel shall obtain the consent of the operating personnel of power plant or substation in advance, and shall perform the work permit procedure in accordance with the relevant regulations of the electrical safety work, and shall not start the testing work until the operating personnel disconnect all the outlet circuits of protection equipment by using pressure plate. 5.2.2.7 The testing site shall be provided with a safe and reliable overhaul test power supply, and it is forbidden to connect test power supply from the operating equipment. 5.2.2.8 Inspect that all metal structures and equipment enclosures in the room where the protection and communication equipment are installed are connected to an equipotential grounding grid. 5.2.2.9 Inspect that the grounding copper bar under the panel where the static protection and control equipment are installed are reliably connected to an equipotential grounding grid. 5.2.2.10 Inspect that the equipotential grounding grid is closely connected to the main grounding grid of the power plant and substation. 5.3 On-site testing of conventional substation 5.3.1 Testing of current and voltage transformers 5.3.1.1 Acceptance of newly installed current and voltage transformers and their circuits. Inspect whether the nameplate parameters of the current and voltage transformers are complete, and whether the end-of-manufacturing certificate and test data are complete. In the absence of the above data, the test department of the relevant manufacturer, capital construction unit or production unit shall provide the following test data: the polarity of all windings, the transformation ratio of all windings and their tappings, the accuracy class of voltage transformer under each capacity, the accuracy class, capacity and internal installation position of each winding of current transformer, the DC resistance (each tapping) of secondary winding, and the volt-ampere characteristics of each winding of the current transformer. 5.3.1.2 Upon completion of the installation of current and voltage transformers, the relay protection testing personnel shall perform the following inspections: a) The transformation ratio, capacity and accuracy class of current and voltage transformers shall meet the design requirements. b) Test the polarity relationship between the windings of the transformer and check whether the polarity mark on the nameplate is correct. Inspect whether the connection mode and polarity relationship of the transformer windings are in accordance with the design and whether the phase sign is correct. c) When conditions permit, apply current to the primary split phase of current transformer to inspect whether the transformation ratio and circuit of working tapping are correct (the polarity and transformation ratio testings of the external transformer used in generator-instrument transformer unit protection and the bushing type current transformer of instrument transformer may be performed when the generator is undergoing short circuit test). d) Apply AC current to the load end from the secondary terminal box of the current transformer to determine the voltage drop of circuit and calculate the impedance between each phase and the neutral line as well as between the phases of current circuit (load of the secondary circuit), and then check whether the determined impedance value meets the error requirement of 10% of transformer by calculating according to the specific working conditions of the protection and the end-of-manufacturing data provided by the manufacturer. 5.3.2 Testing of secondary circuit 5.3.2.1 The testing of secondary circuit may be carried out only after the circuit breaker, current transformer and voltage circuit of the protected equipment are completely disconnected from the circuit of other unit equipment. 5.3.2.2 The secondary circuit of the current transformer shall be tested as follows: a) Inspect the correctness of all secondary wiring of the secondary winding of current transformer and the reliability of crimping of terminal block lead with screw. b) Inspect the grounding point and grounding condition of the secondary current circuit. The secondary circuit of the current transformer shall be grounded separately at only one point; the current circuit combined by several sets of current transformers shall be grounded at one point with direct electrical connection. 5.3.2.3 The secondary circuit of the voltage transformer shall be tested as follows: a) Inspect the correctness of all secondary circuit wiring for secondary and tertiary windings of voltage transformer and the reliability of crimping of terminal block lead with screw. b) For the secondary circuits of several sets of voltage transformers connected through the zero-phase small busbar (N600) of the control room, the N600 shall be grounded at one point only in the control room, and the secondary neutral point of each voltage transformer shall be disconnected at the grounding point of the switching field; in order to ensure reliable grounding, the neutral line of each voltage transformer shall not be connected with a fuse (automatic switch) or contactor, etc. that may be disconnected. A separate secondary circuit that is not directly in electrical relationship with secondary circuits of other transformers may be grounded at one point either in the control room or in the switching field. The 4 incoming lines of switching field from the secondary circuit of the voltage transformer and the 2 (3) incoming lines of switching field from the tertiary circuit of transformer shall be separated and shall not be shared. The open-delta voltage circuit of voltage transformer shall not be connected with a fuse (automatic switch) or contactor, etc. that may be disconnected. c) Inspect whether the metal oxide surge arrester of the secondary neutral point of voltage transformer is installed in compliance with the relevant regulations. d) When the voltage transformer is newly put into operation, inspect whether: the installation position and fusing (tripping) current of all fuses (automatic switches) in the secondary circuit of the voltage transformer are appropriate (the tripping current of automatic switch shall be determined through test), the quality is good, the selectivity can be guaranteed, and the impedance value of coil of automatic switch is appropriate. e) Inspect the contacting reliability of contacts of the fuse (automatic switch), disconnecting switch and switching equipment connected in series in the voltage circuit. f) Measure the DC resistance of each phase from the leading-out terminal of transformer to the voltage busbar of distribution panel in the voltage circuit, and calculate the voltage drop of the voltage transformer at the rated capacity, which shall not be more than 3% of the rated voltage. 5.3.2.4 The insulation of secondary circuit shall be tested as follows: a) The following shall be noted before testing: 1) Before insulation testing of the secondary circuit, it shall be confirmed that the circuit breaker and current transformer of the protected equipment are all powered off, the AC voltage circuit has been disconnected from the circuits of other unit equipment at the voltage switching handle or the distribution box and has been properly isolated from other circuits. 2) During insulation testing, it shall be noted that: the test line shall be firmly connected; after each insulation test, the test circuit must be discharged to the ground; for the busbar differential protection, circuit breaker failure protection and stability control equipment, if it is not possible for all of the protected equipment to be powered off at the same time, the insulation resistance testing can only be performed in sections, that is, when a protected unit is powered off, the insulation resistance of the circuit to which this unit belongs will be determined. b) During the acceptance test of the newly installed protection equipment, all the external leading-in circuits and cables shall be disconnected at the terminal block of protection panel, all the respective terminals of current circuit, voltage circuit, DC control circuit and signal circuit shall be connected, and then the insulation resistance of each circuit to the ground and that between circuits shall be measured with a 1,000V insulation resistance meter, which shall be greater than 10MΩ. c) During periodic testing, the external wiring of terminals of all current circuits, voltage circuits and DC control circuits shall be disconnected at the terminal block of protection panel, and the grounding point of the current and voltage networks shall be disconnected, and then the insulation resistance of each circuit to ground shall be measured with a 1,000V insulation resistance meter, which shall be greater than 1MΩ. d) For the signal circuit with contact output, the insulation resistance of each core of cable to ground and that between the cable cores shall be measured with a 1,000V insulation resistance meter, which shall not be less than 1MΩ. During periodic testing, only the insulation resistance of the cable core to the ground will be measured. e) For the secondary circuit of a voltage transformer grounded with a metal oxide surge arrester, it is required to inspect its wiring correctness and the power-frequency discharge voltage of the metal oxide surge arrester. f) During periodic testing, it is allowed to inspect whether the working state of the metal oxide surge arrester is normal with an insulation resistance meter. Generally, the metal oxide surge arrester shall not be broken down with a 1,000V insulation resistance meter, and shall be reliably broken down with a 2,500V insulation resistance meter. 5.3.2.5 The acceptance testing of the newly installed secondary circuit shall include: a) Observe, clean and make necessary repair and adjustment to all the components (including the operating handle, button, plug, lamp holder, position indicating relay, central signal device and other components related to the protection equipment, as well as the terminal blocks, cables, fuses, etc. in the circuits of these components) of the circuit. b) Apply current to all the intermediate wiring terminals in sequence with the conduction method, and inspect the designation of cable circuit and cable core from the leading-out terminal box of transformer to the operating panel, protection panel and stability control equipment panel or to the distribution box, and check whether the cable book is correctly filled in. c) When an equipment is newly put into operation or is connected into a new circuit, check whether the rated current of the fuse (automatic switch) meets the design or is compatible with the connected load, and also satisfies the coordination between upper and lower levels. d) Inspect that the internal and external wirings of equipment and terminal block on the panel are connected correctly and contact securely, the designation is complete and accurate and is accordance with the drawings and operating procedures. Inspect whether the cable plates on the cable terminal and along the cable laying route are correct and complete, which shall meet the design. e) Test that the DC circuit does not have a parasitic circuit. According to the specific conditions of the circuit design, the testing shall be carried out by the means of disconnecting some equipment e.g., fuse, indicator light, etc.) that may be disconnected during operation in the circuit or closing certain contacts in the circuit. Each set of independent protection equipment shall have a dedicated terminal pair directly leading to the positive and negative power supplies of the DC fuse. All the DC circuits of this set of protection equipment, including the coil network of the outlet relay for tripping, shall only be provided with the DC positive and negative power supplies from this dedicated terminal pair. f) Signal circuit and equipment may not be individually tested. 5.3.2.6 The testing of circuit breaker, disconnecting switch and secondary circuit shall include: a) The relay protection personnel shall be familiar with: the wiring modes (including anti-jump circuit and three-phase inconsistent protection circuit for circuit breaker, and other measures) of the electrical circuits of tripping and closing coils in circuit breaker; the opening and closing condition, switching time, composition method and contact capacity of the auxiliary contacts related to the protection circuit; the working mode of monitoring circuits for air pressure, hydraulic pressure and spring pressure in the secondary operating circuit of the circuit breaker; the wiring diagram for the secondary circuit of circuit breaker; the resistance of the tripping and closing coils of circuit breaker and the tripping and closing currents at rated voltage; the tripping and closing voltages of circuit breaker, which shall meet the requirements of the relevant regulations; the tripping time, the closing time, and the maximum time difference of three-phase contacts not closing at the same time of the circuit breaker, which shall not be greater than the specified value. b) All the adjustment and test work related to the secondary circuit of the protection equipment in the circuit breaker and the disconnecting switch shall be carried out by the relevant personnel who have jurisdiction over the circuit breaker and the disconnecting switch. The relay protection testing personnel shall understand and master the technical performance and debugging results of the relevant equipment, and be responsible for testing the correctness of relevant cable connection from the protection panel to the terminal block of the secondary circuit of circuit breaker (including disconnecting switch) and the reliability of crimping with screw. 5.3.2.7 For newly installed or modified current and voltage circuits, the secondary voltage circuit shall be directly tested under the working voltage, and the wiring correctness of the secondary current circuit shall be tested by the load current. 5.3.3 Testing of panel and protection equipment 5.3.3.1 Precautions during testing The following problems shall be noted during testing to avoid damage to the internal elements and components of the protection equipment: a) The plugins shall not be inserted or pulled out until the power supply of the protection equipment is disconnected, and there shall be measures against damage to the plugins due to static electricity. b) If any problem is found during the debugging process, the cause shall be found at first, and it is disallowed to replace the chip frequently. Where necessary, the chip shall be replaced by using a dedicated puller. During chip replacement, the insertion direction of chip shall be paid attention to; after a chip is inserted, it must be inspected by the second person to confirm no error before power-on testing or use. c) During testing, use of soldering iron shall be avoided as much as possible; if the damaged element needs to be welded on site, it shall be welded by an internal heating soldering iron equipped with a grounding wire or be welded by one which is powered off first. The elements used for replacement shall be qualified products confirmed by the manufacturer. d) When the circuit parameters are measured with an electronic instrument with AC power supply (e.g., oscilloscope, frequency meter, etc.), the measuring terminal of the electronic instrument shall be well insulated from the power supply side, and the instrument enclosure shall be grounded at the same point as the protection equipment. 5.3.3.2 External inspection of protection equipment The protection equipment shall be subjected to the following external inspections: a) Whether the actual composition of the protection equipment is consistent with the design, for example: configuration, model, and rated parameters (rated voltage of DC power supply, rated AC current and voltage, etc.) of the equipment. b) The process quality of the main and auxiliary equipment, and the quality of the materials used for the conductors and terminals. The fastness of all welding points and the contact reliability of all plugins in the protection equipment are problems of the manufacturing process quality, and the manufacturer shall be mainly responsible for quality assurance of products. When conducting testing of newly installed protection equipment, the testing personnel shall only conduct random testing. c) The signs on the panel shall be correct and complete and in accordance with the drawings and operating procedures. d) Inspect that the EMI mitigation devices and measures installed in the input circuit and power supply circuit of the protection equipment meet the technical requirements of the relevant standards and the manufacturer. These EMI mitigation devices and measures shall be kept in good condition throughout the testing of the protection equipment. e) Remove the pressure plates that do not participate in normal operation on the protection panel, or take other measures to prevent mis-switching on. f) Main items of periodic testing: inspecting whether the inside and outside of the protection equipment are clean and free of dust; cleaning the dust on the circuit board and the terminal block in the panel; and inspecting whether: the small switch, reel and button of the equipment are in good condition, the display and text are clear, the printed circuit board of each plugin is damaged or deformed and the connection is good, the elements on each plugin are well welded and the chip is tightly inserted, the converter and relay on each plugin are fixed without looseness, the screws of horizontal terminal block of the equipment are tightened and the rear panel wiring connection is good; inspecting, setting and recording the position of selective jumper and toggle switch in the plugins of the protection equipment with the method described in the technical instructions of the protection equipment according to the actual needs. 5.3.3.3 Insulation test The procedures and requirements of insulation test are as follows: a) Perform insulation test only at the acceptance testing of newly installed protection equipment. b) Pull out the plugins according to the requirements of the technical instructions of the protection equipment. c) Respectively short-circuit the terminals of AC voltage circuit, AC current circuit, DC power supply circuit, tripping and closing circuits, on-off input circuit, plant automation system interface circuit and signal circuit on the inner side of the terminal block of protection panel. d) Disconnect the control circuits from other protection equipment. e) Disconnect the printer from the protection equipment. f) The shield of all transformers in the protection equipment shall be reliably grounded. When the insulation resistance of a certain group of circuits to ground is measured, the other groups of circuits shall be grounded. g) Measure the insulation resistance value with a 500V insulation resistance meter, which shall be greater than 20MΩ. Discharge each circuit to ground after testing. 5.3.3.4 Power-on inspection The procedures and requirements for power-on inspection are as follows: a) Power on the protection equipment and the equipment shall be able to work normally. b) Inspect and record the hardware and software version Nos., check codes and other information of the equipment using the method described in the technical instructions of the protection equipment. c) Calibrate the clock. 5.3.3.5 Working power supply inspection The procedures and requirements for working power supply inspection are as follows: a) For microprocessor-based protection equipment, all plugins are required to be inserted. b) Test with 80% of the rated working power supply: the protection equipment shall work stably. c) Power self-starting test: switch on the power of the DC power plugin and slowly adjust the DC test power from zero to 80% of the rated power value. Consequently, the running light on the protection equipment shall be on, and the equipment is free of abnormity. d) DC power supply switch-on-off test: switch on and off the DC working power supply under the rated voltage for 80% of DC power supply three times, the inverter power supply shall start reliably, the protection equipment does not malfunction, and does not missend any signal. e) There is no abnormality during the recovery after power failure in the protection equipment, and the equipment shall work stably and normally after being powered on. f) At the moment being powered on and off, the protection equipment shall not send abnormal data, and the relay shall not malfunction. g) During the periodic testing, it shall also be inspected whether the inverter power supply is close to the minimum time between failures as specified in DL/T 527-2013, and shall be timely replaced if it is. 5.3.3.6 Analog-to-digital conversion system testing Analog-to-digital conversion system testing shall be carried out as follows. a) Test zero drift. It is required not to input AC current and voltage into the protection equipment when it is subjected to such a testing. Observe that the zero drift value of the equipment over a period of time meets the technical specifications of the equipment. b) Testing of the amplitude value and phase accuracy of each current and voltage input. During the acceptance testing of the newly installed protection equipment, input the current and voltage of different amplitude values and phases respectively according to the test method specified in the technical instructions of the equipment, and observe that the sampling value of the equipment meets the technical specifications of the equipment. It is allowed to only input the current and voltage of different amplitude values separately during full testing, and only the rated current and voltage separately during part-item testing. c) Technical requirements. They shall meet the relevant requirements of DL/T 478-2013. 5.3.3.7 On-off input circuit testing The on-off input circuit testing shall be carried out as follows: a) During the acceptance testing of the newly installed protection equipment: according to the test method specified in the technical instructions of the equipment, add the energizing quantity to the on-off input circuit of all the leading-in terminal blocks in sequence at the terminal blocks of the protection panel and observe the behavior of the equipment. According to the test method specified in the technical instructions of the equipment, connect and disconnect the pressure plate, turn the handle respectively and observe the behavior of the device. b) During full testing, it is only required to add the energizing quantity in sequence to the on-off input circuits that have been put into use, and observe the behavior of the equipment. c) Part-item testing may be carried out along with the overall test for the equipment. d) Technical requirements: the starting voltage value of the high-voltage input-circuit relay shall not exceed 0.7 times the rated voltage, and shall not be less than 0.55 times the rated voltage, and the relay driving power shall not be less than 5W. The input-circuit shall be connected and disconnected separately, and the input of the equipment shall be displayed correctly. The on-off input of the equipment shall be defined by positive logic, that is, the on-contact is “1” and the off-contact is “0”. The input’s name shall be as described in the requirements of the standard. If the same input is shared by several types of protection, it shall be transmitted separately to each type of protection. 5.3.3.8 Inspection of switching value output contacts and output signals The inspection of switching value output contact and output signal shall be carried out as follows: a) During the acceptance testing of the newly installed protection equipment: according to the test method specified in the technical instructions of the equipment, observe the on-off state of all the output contacts and output signals of the equipment in sequence at the terminal blocks of the protection panel. b) During full testing, according to the test method specified in the technical instructions of the equipment, observe in sequence the on-off state of all the output contacts and output signals of the equipment already put into use at the terminal blocks of the protection panel. c) Part-item testing may be carried out along with the overall test for the protection equipment. d) Technical requirements: the output contacts of the protection equipment shall be able to be reliably maintained and returned, the contact is good and not jittery, and the action delay of the equipment shall meet the engineering and design requirements. If a set of exit pressure plates or the same alarm signal is shared by several types of protection, these types of protection shall be transmitted separately to the exit pressure plates and protection panel terminal blocks.

Contents of DL/T 995-2016

Foreword II 1 Scope 2 Normative references 3 Terms and definitions 4 General 5 Testing of relay protection and stability control equipment in conventional substation 6 Testing of relay protection and stability control equipment in smart substation Annex A (Informative) State overhaul of relay protection and stability control equipment Annex B (Normative) Testing items for commonly used relays Annex C (Normative) Testing items for various equipment of conventional substation Annex D (Normative) Testing methods for merging unit and smart terminal of smart substation