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P R OT E C T I O N KBCH 120, 130, 140 Differential Protection for Transformers and Generators Type KBCH relays offer biased differential current, restricted earth fault and overfluxing protection primarily for the protection of two or three winding power transformers, auto transformers or generator-transformer units. The KBCH provides these features in a very compact and space – efficient case size, for ease of installation. All models are three phase units with internal vector group compensation and line current transformer ratio correction, thus eliminating the need for interposing transformers. Figure 1 KBCH relay Up to four biased current inputs per phase can be provided to cater for power transformers with more than two windings and/or more than one circuit breaker controlling each winding, as in mesh or one-and-a-half circuit-breaker busbar arrangements. Versions are available that can accommodate a mixture of 1A (HV) and 5A (LV) CTs, as well as standard models having all 1A or all 5A CTs. MODELS AVAILABLE > KBCH120 offers 2 bias inputs per phase for the protection of a two-winding power transformer. Customer Benefits • Biased differential protection • Restricted earth fault protection • Overfluxing protection • Integral CT ratio and vector group compensation • Measurement of phase, differential and bias currents AREVA T&D > KBCH130 offers 3 bias inputs per phase for the protection of a three-winding power transformer or a two-winding power transformer with 2 sets of CTs on one winding. > KBCH140 offers 4 bias inputs per phase. All models are available with either 1A or 5A inputs on the primary and secondary side. Alternatively the KBCH 120 and 140 can be provided with 1A CTs on the high voltage windings and 5A CTs on the low voltage windings. 3 2 Operate Differential current (xIn)= pe I1 + I1 + I3 + I4 In addition to the biased differential protection, restricted earth fault protection has been included to cover a larger percentage of the transformer windings. Figure 7 shows some typical restricted earth fault applications. The differential protection has been designed to restrain when the transformer is overfluxed so that an instantaneous trip is not issued for transient overfluxing. Since a transformer cannot withstand a severe overfluxing condition indefinitely, time delayed overfluxing protection and an alarm stage has been incorporated. Contacts that monitor the status of external plant, such as Buchholz protection and temperature measuring devices, can be connected to any of the eight control inputs that are available. Each input can be routed to any number of the output relays via a variable time delay if required. 0% Restrain 8 1 Setting range 0.1 - 0.5In slo able Allow tio error ra 20% 20% 0 slope 1 2 3 Figure 2 Biased differential characteristic A B C FUNCTIONS > Biased differential element Figure 3 Each relay, contains a biased differential element per phase with a characteristic as shown in Figure 2. The KBCH has a dual slope bias characteristic. The initial slope of 20%, from zero to rated current, ensures sensitivity to faults whilst allowing for up to 15% mismatch when the power transformer is at the limit of its tap range, in addition to current transformer ratio errors. At currents above rated, extra errors may be gradually introduced as a result of CT saturation. The bias slope is therefore increased to 80% to compensate for this. The current waveform associated with magnetising inrush is characterised by a period of each cycle where its magnitude is very small, as shown in Figure 3. By measuring the time of this period of low current, an inrush condition can be identified. Overfluxing restraint is conditioned by the percentage of fifth harmonic current present. > High set differential element An additional high set instantaneous differential element is provided to ensure rapid clearance of heavy faults. This element is essentially peak measuring to ensure fast operation for internal faults with saturated CTs. 2>3 4 | I1 | + | I2 | + | I3 | + | I4 | Effective Bias (xIn)= 2 Typical magnetising inrush waveforms > Restricted earth fault protection Greater sensitivity for earth faults is obtained by including restricted earth fault protection. A separate element per winding is provided. An externally mounted stabilising resistor will be necessary for optimum performance. In applications where heavy internal earth fault levels can occur and where a high stabilising resistor setting is used, a voltage limiting, non-linear resistor may be required. > Overfluxing Alarm and Tripping Protection A single phase-phase connected voltage input is provided to enable overfluxing detection. Alarm and tripping characteristics, which are based on a measurement of the voltage/frequency ratio, are provided. The alarm is definite time delayed whilst the trip characteristic may be selected as either definite time, or an IDMT curve (Figure 4). Integrated transformer protection in a small package, for ease of fitting / retrofitting. CONFIGURATION Operating time as a function of the actual excitation and the set starting value for different time multiplier settings (K) time (s) The setting of logic function links, together with the input and output masks, define the way the relay will operate. This allows: 1000 100 • Selection of features K=6 • Implementation of user defined logic using auxiliary timers (8 available) • Control of the integral disturbance recorder. K=4 K=2 10 K=5 > Inputs and outputs K=1 1 1 KBCH has 8 optically isolated inputs which may be reassigned by the user with any of the available functions from the setting menu. There are 8 programmable outputs, each comprising a relay with 1 normally open contact. A dedicated watchdog contact with 1 normally open and 1 normally closed contact is also available. > Alternative setting group Two setting groups are provided. This allows the user to set one group to normal operating conditions while a second group may be set to cover alternative operating conditions. ANCILLARY FUNCTIONS > Measurements The relay can display the magnitude of phase currents for each input, differential current and average bias current. The power system frequency is also displayed. > Fault records The fault flags for the last five faults are recorded by the relay. Additional records of the magnitude of the fault currents are also stored for the last fault. 1.1 1.2 1.3 M= Figure 4 1.4 1.5 (V/f) (V/f) setting Inverse time characteristic for overfluxing protection > Event records Fifty events can be stored in a buffer. Software is available to allow the events to be accessed remotely by a PC via the communications system. > Disturbance records (Oscillography) The analogue channels record up to nine phase currents (three per transformer winding) three differential currents, three average bias currents and the voltage. The digital channels record the status of the output relays and control inputs. > Power-on diagnostics and self monitoring Power-on diagnostic tests are carried out by the relay when it is energised. Continuous self-monitoring, in the form of watchdog circuitry and memory checks are also performed. In the event of a failure, the relay will either lock out or attempt a recovery, depending on the type of failure detected. Figure 5 Basic communication system Relay 32 Relay 4 Desktop computer PC Relay 3 Relay 2 Relay 1 Protocol converter KITZ IEC870-5 RS232 K-Bus RS485 1.6 USER INTERFACE > Relay interconnection The relays can be interconnected via a shielded, twisted wire pair known as K-Bus. The K-Bus is connected through a protocol converter known as KITZ, either directly or via a modem, to the RS-232 port of the PC. This system allows up to 32 relays to be accessed through one RS-232 communications port (Figure 5). > Front panel user interface The features of the relay can be accessed through a menu-driven system. The user can move around the menu by means of the keys on the relay frontplate. This can be done with the cover in place, but any change to the settings requires the cover to be removed. > Password protection > Remote access user interface The menu table can also be accessed via the remote communications facility. This allows all of the menu cells in a column to be displayed simultaneously on the screen of a PC. Password protection is provided on settings which alter the configuration of the relay, any accidental change to which could seriously affect the ability of the relay to perform its intended function. Figure 6 P1 A Typical application diagram KBCH120 P2 S1 B P2 S2 HV P1 S2 LV C S1 A B C 63 69 64 65 70 71 66 67 72 73 68 74 75 KBCH 120 21 76 77 22 23 78 79 24 25 80 81 26 27 82 83 28 84 4 HV lo> (see Figure 10) A B A C A B C C B Phase rotation AC/DC supply Vx LV1 lo> (see Figure 10) WD 13 b RL2 18 4 29 RL4 6 31 32 8 33 34 9 10 35 36 37 38 39 40 41 42 43 44 45 46 Logic input common (1) 47 48 Initiate aux. timer 3 L3 49 50 51 52 53 54 55 56 66 67 68 69 70 71 72 73 74 75 76 77 78 21 22 79 80 23 24 81 82 25 26 83 84 27 28 13 14 17 18 19 20 SCN 36 Trip Id > A,B,C Id >> A,B,C Io > HV,LV1,LV2 V/f trip Initiate aux. timer 1 L1 46 48 RL5 Initiate aux. timer 4 L4 Initiate aux. timer 5 L5 See Note 4 Initiate aux. timer 6 L6 Initiate aux. timer 7 L7 Logic input common (2) 44 Trip Id > A,B,C Id >> A,B,C Io > HV,LV1,LV2 V/f trip Trip 31 Id > A,B,C Id >> A,B,C Io > HV,LV1,LV2 V/f trip Tap up 35 Tap down 37 RL6 Initiate aux. timer 2 L2 40 33 Initiate aux. timer 0 L0 Module terminal blocks viewed from rear Id > A,B,C Id >> A,B,C Io > HV,LV1,LV2 V/f trip 29 30 7 65 Trip 42 RL3 1 5 Relay failed 38 c 17 3 32 34 RL1 a 64 Relay healthy 30 RL0 n 63 5 WD N 57 6 3 14 50 39 Alarm = V/f alarm 41 RL7 52 43 Trip Id > A,B,C Id >> A,B,C Io > HV,LV1,LV2 V/f trip 57 45 47 1 Case earth connection 49 54 51 53 56 See Note 4 K-Bus communications port SCN 7 55 8 +48V field voltage Notes: 1. (a) 4>5 CT shorting links make before (b) and (c) disconnect. 2. VT input must be supplied with phase - phase voltage. Connections are typical only. (b) Short terminals break before (c). 3. Earth connections are typical only. (c) Long terminals. 4. SCN = Screen connection for K-Bus. (d) Pin terminal (PCB type) KBCH : Quick to configure, simple to test A B P1 P2 S1 P2 S2 P1 S2 S1 C A B C P2 P1 S2 Figure 7 S1 See Note 2 See Note 1 63 69 64 65 70 71 RS See Note 2 66 67 72 73 68 RS See Note 1 74 75 KBCH 120 21 76 77 22 23 78 79 24 25 80 81 26 27 82 83 Notes: 1. See Service Manual R8530 for the setting of the external stabilising resistor. 28 84 2. Optional voltage limiting non-linear resistor (see Service Manual R8530). > Operating time > Technical Data Nominal (Vx) Operative Range (V) 24–125V dc or 110V 50/60Hz ac 20–150V dc 48–250V dc or 220V 50/60Hz ac 33–300V dc Absolute Maximum (V) low set high set REF typically typically typically 30 – 35ms 15ms 20 – 40ms 190V crest Vector group and ratio correction 50–133V ac HV Ratio Cor (primary) 380V crest LV1 Ratio Cor (secondary) LV2 Ratio Cor (tertiary) 87–265V ac Field voltage supply for optically isolated digital inputs (current limit: 60mA) 48V dc Yy0 (0deg), Yd1 (–30deg), Yd2 (–60deg), Yd3 (–90deg), Yd4 (–120deg), Yd5 (–150deg), Yy6 (+180deg), Yd7 (+150deg), Yd8 (+120deg), Yd9 (+90deg), Yd10 (+60deg), Yd11 (+30deg), Ydy0 (0deg), Ydy6 (+180deg), HV Ratio Cor (primary) 0.05 to 2 in steps of 0.01 LV1 Ratio Cor (secondary) 0.05 to 2 in steps of 0.01 LV2 Ratio Cor (tertiary) 0.05 to 2 in steps of 0.01 Typical restricted earth fault connections > Watchdog relays > Digital Inputs 1 make and 1 break Optically isolated inputs 8 energised from the 48V field voltage • Make: 10A and carry for 0.2s • Carry: > Contacts • Break: 5A continuous DC • Output relays 8 single make AC > Contact ratings • Make: 30A and carry for 0.2s • Carry: 5A continuous • Break: DC AC 30W resistive 15W inductive (L/R = 0.04s) 1250VA (5A maximum) Subject to maxima of 5A and 300V 50W resistive 25W inductive (L/R = 0.04s) 1250VA (5A maximum) Subject to maxima of 5A and 300V TRANSFORMER CONFIGURATION Setting No. of bias inputs Configuration Applicable to: HV HV + LV 2 KBCH120/130/140 LV HV HV + LV1 + LV2 3 KBCH130/140 LV2 LV1 HV HV (x2) + LV 3 KBCH130/140** LV HV HV + LV (x2) 3 KBCH130/140 LV HV HV (x2) + LV1 + LV2 4 Only KBCH140 LV2 LV1 HV HV + LV1 (x2) + LV2 4 LV1 LV2 Only KBCH140** HV HV (x2) + LV (x2) 4 Only KBCH140 LV 6>7 Transformer, generator or reactor differential, and busbar protection (arrangements with up to 4 feeders) CASE 4 holes ø4.4 200 The KBCH unit is housed in a size 8 Midos case as shown in Figure 8. 155.4 24 168 Figure 8 Push button projection 10 max Case outline size 8 159 203 Panel cut-out: Flush mounting fixing details 32 212 25 min. 177 157 max. Reset 206 Flush mounting All dimensions in mm INFORMATION REQUIRED WITH ORDER Unit type KBCH1 2 bias inputs per phase 3 bias inputs per phase 4 bias inputs per phase Configuration: Standard Case Size: Size 8 Midos flush mounting Auxiliary voltage: 24/125V 48/250V Rating: Vn = 100/120V In = 1A Vn = 100/120V In = 5A * Vn = 100/120V In = 1A/5A Language: English French German Spanish * Not available for KBCH 130. 0 2 3 4 0 1 W 1 2 5 L M P E F G S 11 AREVA TRACK RECORD TRANSFORMER DIFFERENTIAL PROTECTION >> Over 34 000 predecessor MBCH relays shipped. >> Over 10 500 KBCH differential relays delivered since launch in 1994. >> MiCOM P63x series available for fully integrated transformer protection, with extra overcurrent protection and Programmable Logic (PSL). >> KVGC 202 available for voltage AUTOMATION-L3-KBCH-BR-04.05-0910-GB - ©2005 AREVA - AREVA, the AREVA logo and any alternative version thereof are trademarks and service marks of AREVA. MiCOM is a registered trademark of AREVA. All trade names or trademarks mentioned herein whether registered or not, are the property of their owners. - 389191982 RCS PARIS - Printed in France - SONOVISION-ITEP regulation (tap change control). AREVA T&D Worldwide Contact Centre: http://www.areva-td.com/contactcentre/ Tel.: +44 (0) 1785 250 070 www.areva-td.com www.areva-td.com/protectionrelays Our policy is one of continuous development. Accordingly the design of our products may change at any time. Whilst every effort is made to produce up to date literature, this brochure should only be regarded as a guide and is intended for information purposes only. Its contents do not constitute an offer for sale or advise on the application of any product referred to in it. We cannot be held responsible for any reliance on any decisions taken on its contents without specific advice.