RCS-915A Busbar protection equipment
RCS-915A Busbar Protection
Application
RCS-915A is a micro-processor based high-speed, selective and differential protection equipment for busbar system of any voltage and any configuration, such as single busbar, sectioned single busbar, double busbars, etc.. Up to 21 feeders (bay units, bus couple included) could be comprised in this system. Besides busbar differential protection, other functions like busbar dead zone protection, bus couple energizing protection, bus couple overcurrent protection and circuit breaker failure protection are also equipped with it.
General
The equipment uses an integral front panel and closed cabinet with high immunity. Commissioning and maintenance in the site could be done easily by dedicated tuning and testing set developed by our company. A 14 digit A/D converter is used for sampling unit and high accuracy of the sampling could be achieved. Co-process of high-speed digital signal processor (DSP) and 32 bits main micro-processor could ensure high speed and high accuracy of the whole protection system. A complex programmable logic device (CPLD) is used as the flexible and reliable tripping logic unit.
Data and logic are processed in protection module and management module with same hardware respectively. The protection module carries out functions of all protection algorithm, tripping logic, event record and record printing and communication. DSP1 implements algorithm for busbar differential protection, bus couple energizing protection, bus couple overcurrent protection and dead zone protection while DSP2 implements algorithm for circuit breaker failure protection. CPU on this module interchanges data including AC sampling value and calculation results of protection with DSP. Based on the calculation results, the CPU processes the tripping logic, event record and event report.
The management module carries out calculation of the starter and record of power system disturbance. It acquires also the same analog and status quantities as the protection module does. The algorithm used by DSP in this module is also the same with that in protection module. However result of calculation of DSP1 is not used for tripping decision but closing power source of tripping relays and that of DSP2 is used for initiating the fault record.
Real-time voltage of busbar, currents in the feeders, layout and operation mode of the busbar could be displayed in LCD screen clearly. Man-machine interface consisted of LCD screen and a keypad on the panel is ver friendly to the user.
A serial port of man-machine interface is used for communication with a PC. All operation including configuration and monitoring could be done not only by the keypad mentioned above but also a PC. Man-machine interaction could be done more conveniently on PC with a dedicated Windows based software package.
Features
- Low-impedance busbar protection is employed.
- Current ratio could be configured by software separately for each TA (current transformer) and the equipment allows to use existing TA with different current ratio in one protection system.
- Starter with adaptive floating threshold consisting of deviation of power frequency component (DPFC) of busbar voltage is used for the equipment. It could not be initiated in case of power swing.
- Strong ability on resistance to TA saturation could be got by a new adaptive weighted element while sensitivity to internal fault could still be kept high. Maloperation of the equipment will be prevented in case of near external fault and high saturation of TA. However, if an internal fault occurs or an external fault evolves to an internal one, the equipment will operate within 10 ms typically.
- The equipment uses principle of combination of DPFC percentage differential protection and normal percentage differential protection. Its performance could be hardly influenced by power angle before fault. Its adaptability to resistance fault and hence sensitivity to internal fault could be highly increased then. (For 220 kV system, when resistance of an internal fault is 100
, the equipment could operate within 15 ms.)
- Operation mode of the busbar could be discriminated by the equipment through position contacts of the line switches. Meanwhile self-diagnostic will be executed with these contacts. If current is detected in a section of the busbar while the corresponding line switch is in "off" position, an alarm will be sent.
- Format of the fault record is compatible with international COMTRADE format and convenient to postmortem data processing. The record could be led out via a serial port for observing or printing.
- RS-485 or optic fiber ports (optional) are equipped and protocol of IEC 60870-103 is used for communication within the whole protection system.
Technical data
| Ratings DC control voltage 220 V, 110 V Tolerance +15% - -20% AC voltage 100 V /  3AC current 5 A, 1 A Line voltage for recloser 100 V, 57.7 V Frequency 50 Hz |
Bus couple overcurrent protection Pick-up range 0.1 - 20 In Step 0.01 A Timer 100-1000 ms Step 10 ms |
| Power consumption AC current circuit at rated current < 0.5 VA /  ( In = 5 A)< 0.25 VA / ( In = 1 A)AC voltage circuit at rated voltage < 0.5 VA / DC control circuit quiescent 50 W energized 70 W |
Recorder Number of events to be recorded 32 Number of oscillograms to be recorded 8 |
| Communication Serial port 1, for printer 2, for PC Protocol IEC 60870-5-103 | |
| DC Power supply For internal circuit  15 V, tolerance 0.2 V+ 5 V, tolerance 0.15 V For opto-coupler 24 V, tolerance 2 V |
Ambient temperature Normal operation -5  - 40 Extreme range - 10 - 55 |
| Starter Differential current starter Pick-up range 0.3 - 1.5 In Step 0.01 A Deviation of power frequency component voltage Starter  UPick-up value 0.05 Un |
EMC test 1 MHz bursts disturbance IEC 60255-22-1, classIII Electrostatic discharge IEC 60255-22-2, classIII Fast transient disturbance IEC 60255-22-4, classIV Radio frequency emission IEC 60255-22-3, class III 10 V/m, ( 25-1000 ) MHz |
| Differential protection Percentage restraint coefficient Pick-up range 0.5 - 0.9 Tolerance of current setting < 5% Operation time <15 ms (at 2  setting value) |
Insulation test Insulation IEC 60255-5 2 kV, AC 1 min Impulse IEC 60255-5 5 kV, 1.2/50  s, 0.5J |
| Shelf Weight 45 kg Dimensions width 487 mm (19") height 530.4 mm (12 U) depth 285 mm Flush type mounting, panel cutout 450 mm 531.5 mm | |
| Breaker failure protection Pick-up range 0.1 - 2 In Step 0.01 A Timer 100-1000 ms Step 10 ms |