AUGUST 2001 APPLICATION AND COMMISSIONING MANUAL MIT161 RELAY EASUN REYROLLE LIMITED

Transcription

1 AUGUST 2001 APPLICATION AND COMMISSIONING MANUAL MIT161 RELAY EASUN REYROLLE LIMITED 1

2 Issue No : 2nd Issue Date of Issue : Department : TP-CTS 2

3 SENSITIVE CURRENT PROTECTION PROTECTION HEALTHY STARTER TRIP MIT 161 EASUN REYROLLE INDIA MIT161 RELAY 3

4 CONTENTS PAGE APPLICATION 5 INSTALLATION 12 COMMISSIONING 18 WIRING DIAGRAM 24 4

5 APPLICATION 1. INTRODUCTION The type MIT161 numerical sensitive current protection relay combines the power and flexibility of microprocessor technology. The relay is especially tuned to suit applications where low settings, low burden and rejection of harmonic currents become a necessity. The relay is suitable for high resistance earth fault protection and capacitor bank unbalance current protection. 2. CHARACTERISTICS MIT161 relay has two stage protection i.e. earth fault element and lowset element. Earthfault element is provided with DTL characteristic and the lowset element is provided with DTL & IDMTL (Standard Inverse 3 sec, Standard Inverse 1.3 sec, Very Inverse Extremely Inverse and Long Time Inverse) characteristics. 3. RESET TIME DELAY The lowset element IDMTL characteristic is also provided with reset time delay characteristic for detecting Flashing faults. The increasing use of plastic cables, both, conventionally buried types and aerial bundled conductor types have given rise to the number of "pecking" or "flashing intermittent faults on distribution systems. At the fault position, the plastic melts and temporarily reseals the faulty cable for a short time, after which the insulation fails again. The same phenomenon has occurred in joint boxes where an internal flashover temporarily reseals. The behaviour of different types of over current relays under flashing fault condition is compared in Fig.1. The repeating process often caused electromechanical disc relays to "ratchet up and eventually trip the faulty circuit provided that the reset time of the relay was longer than the time between successive flashes. Early electronic IDMTL relays with instantaneous reset features were not at all effective in dealing with this condition and only tripped after the flashing fault had developed into a solid permanent fault. To overcome this the MIT161 relay has a reset time setting which can be user programmed to be either instantaneous or delayed from 1 to 60 seconds in step of 1 sec. On the other hand, on overhead line networks, particularly where reclosers are incorporated in the protected system, instantaneous resetting is desirable to ensure that, on multiple shot reclosing schemes, correct grading between the source relays and the relays associated with the reclosers is maintained. 5

6 FAULT CURRENT Flashing Faults Fault becomes permanent ELECTROMECHANICAL SLOW RESET TRIP STATIC INSTANTANEOUS RESET TRIP NUMERICAL (MIT) DELAYED RESET TRIP Figure 1 Flashing Fault Protection 4. SYSTEM EARTH FAULT Distribution Feeder Fault Current magnitude depends upon the amount of fault resistance and it can vary from reasonable value to a very low value. MIT161 has two elements, which can be set for IDMTL and SEF protection to get complete protection for line ground fault. R Y B MIT 161 Fig. 2. CT Residual Connection. Fig.2 shows the CT residual connection for detecting earth faults. 6

7 Fig.3 shows core balance CT connection for sensitive earth fault application. R Y B MIT 161 Fig. 3 CBCT Connection 5. CAPACITOR UNBALANCE CURRENT PROTECTION MVT161 can be used for unbalanced current protection of double star, delta and singlephase capacitor banks. MIT 161 INSTALLATION Fig.4. Double Star Capacitor Bank Neutral Unbalance Protection. 7

8 MIT 161 Fig.5. Single phase capacitor bank/ Delta connected bank unbalance protection. Fig.5. shows single-phase capacitor bank / 3 phase delta connector bank unbalance protection. When the relay is used for 3-phase delta connected bank unbalance protection, 3 MIT 161 relays have to be used. 6. TECHNICAL INFORMATION 6.1. Rating 1 Amp / 5Amps 6.2. Frequency 50 Hz 6.3. Auxiliary Supply Nominal Voltage Voltage Range 24 / 30 / 48 / 110V DC V DC 48/110/220 V DC or 110V AC V DC 6.4. Settings Earth fault element 0.5% to 25% in steps of 0.5% Low set element 0.5% to 25% in steps of 0.5% Time Multiplier to 1.0 in steps of Reset Time 0 to 60 sec in steps of 1 sec 8

9 6.5. Operating Characteristics Earth Fault element Low set element DTL Operating time Definite Time Lag (DTL) Standard Inverse 3 sec (SI3) Standard Inverse 1.3 sec (SI1) Very Inverse (VI) Extremely Inverse (EI) Long Time Inverse (LTI) or Definite Time Lag (DTL) 0 to sec in steps of 0.01 sec IDMTL Operating Time can be calculated as follows T = K x T M (I/I S ) α - 1 Where I Fault current I S Setting current T M Time Multiplier Setting SI3 K = 0.14 α = 0.02 SI1 K = α = 0.02 VI K = 13.5 α = 1.0 EI K = 80.0 α = 2.0 LT1 K = α = Accuracy Starter 104% of setting ± 4% Reset 94% of setting Repeatability ± 1% IDMTL Operate Time ± 5% or ± 35 m.sec DTL Operate Time ±1% or ± 35 m.sec Output Contacts THE RELAY HAS 5 OUTPUT RELAYS 1. Common trip / alarm relay 2 N/O 2. Common Starter 1 C/O 3. Earth Fault operated 1 N/O 4. Low set operated 1 N/O 9

10 5. Protection Unhealthy 1 N/C CONTACT RATING Carry continuously Make & Carry Break 5 A AC rms or DC 20A for 0.2 sec 50W DC with a max. of 300V or 5A DC L/R 40msec 6.8. Burden AC (1 Amps) VA at 5mA 0.06VA at 250mA AC (5 Amps) VA at 25mA 0.2 VA at 1.25A DC (Quiescent) 5W 7. ENVIRONMENTAL 7.1. Temperature IEC /2 Operating Range - 10 C to + 55 C Storage Range - 25 C to + 70 C 7.2. Humidity IEC days at 40 C and 93% RH 7.3. Transient Over voltage IEC KV, 1.2/50µs, 0.5J between all terminals and Earth or between any two terminals without damage or flashover Insulation IEC KV rms for 1 min between all terminals and earth 2.0KV rms for 1 min between Independent circuits 1.0KV rms for 1 min across normally open contacts Variation 7.5. High Frequency Disturbance IEC , Class III Variation 2.5KV Common (Longitudinal) Mode 3% 1.0KV series (Transverse) mode 3% 10

11 7.6. Electrostatic Discharge IEC , Class III Variation 6KV Contact Discharge 5% 8KV Air Discharge 5% 7.7. Radio Frequency Interference IEC , Class III Variation 20MHz to 1000MHz, 10 V/ m 3% 7.8. Fast Transient IEC , Class IV Variation 4KV, 5/50nS, 2.5KHZ repetitive 5% 7.9. Vibration (Sinusoidal) IEC , Class Shock and Bump IEC , Class 1 8. CUTOUT DETAILS 151 x 151mm (2/3 Vedette draw out case) 11

12 INSTALLATION 1. UNPACKING On receipt, remove the relay from the carton box in which it was received and inspect it for obvious damage. It is recommended that the relay is not removed from the relay case. To prevent the possible ingress of dirt, the sealed polythene bag should not be opened until the relay is to be used. If damage has been sustained, please inform Easun Reyrolle Ltd., for necessary action. 2. STORAGE When the relay is not required for immediate use, it should be returned to its original carton and stored in a clean dry place. 3. HANDLING The relay s electronic circuits are protected from damage by static discharge when the relay is housed in its case. When relay is withdrawn from the case, static handling procedures should be observed: Before removing the relay from its case the operator must first ensure that he is at the same potential as the relay, by touching the case. The relay must not be handled by any of the relay terminals at the rear of the chassis. Ensure that anyone else handling the relay is at the same potential. As there are no user serviceable parts and adjustable user settings inside the relay, there should be no requirement to remove any modules from the chassis. If any modules are removed or tampered with, then the guarantee will be invalidated. 4. MOUNTING Mount the relay using 2 nos. mounting straps and 1no earth strap. Ensure that an earth wire is connected to the earth strap from the earth terminal 23. Terminal 23 should be directly connected to the system ground. Only settings or trip details can be accessed via the pushbuttons when the cover is fitted. To change the settings the front cover has to be removed. Sealing arrangement is provided in one of the four knurling screws fitted on the cover. Sealing can be done using a sealing wire. Thus mechanical interlock is provided to avoid unauthorized setting change. 12

13 5. EQUIPMENT 5.1 Current tap Selection MIT relays are suitable for 1A or 5A application. However the relays are internally wired for either 1A or 5A as per the customer requirement. Internal wiring are to be changed (Faston crimp connections) for changing the relay rating from one to other. To ensure the current rating (I R ) of the relay, check the connection of CT wires connected to the bottom TB (Terminal Block) at the rear of the chassis as per the following table: For 1A Terminal No. Ferrule No. of CT of TB wire(black) 11 11A For 5A Terminal No. Ferrule No. of CT of TB wire(black) 11 11B Following are the steps to change the current rating of the relay from 1A to 5A. 1. Identify 11 th terminal from number strip on bottom terminal block at the rear of the chassis. 2. The black colour wire 11A is inserted to 11 th terminal of TB. 3. First, carefully lift the PVC boot of the wire by means of a tool (like nose Plier) to expose terminal 11A. 4. Hold the crimp by means of the same tool at the crimp point and lift to remove from the fixed terminal. Remove the 11B wire from the terminal parking rack (fixed on terminal block) and insert the crimp of 11B wire on to the terminal No.11 by means of the tool. Insert "11A wire back to the terminal parking rack. 13

14 Ensure proper insertion of 11B wire by pulling the wire by hand and the wire Should not come off the terminal. 5. Push the boot of 11B wire to completely cover the crimp. Same procedure in reverse is to be followed to change from 5A to 1A Human Machine Interface (HMI) The user friendly HMI provided on the front panel has following features: Six digit, 7 segment LED display (First two digits are Red colour and other four digits are Green colour). First two digits (Red) displays the main menu or type of fault when selected for Setting mode or Trip indication respectively. Remaining four digits (Green) displays Sub menu or "Trip" indication respectively. 2. Green LED - Protection healthy indication 3. Yellow LED (STARTER) - Starter indication 4. Red LED (TRIP) - Trip indication, 5. Red LED (in Key) - Sub Menu 6. Key - Up scrolling 7. Key - Down scrolling 8. Key - Enter / Reset / Cancel / To check Version 5.3. How to operate HMI Remove the front cover by unscrewing the four knurling screws. Apply DC supply. Terminals 22,24 and 23 are for positive, negative and earth respectively as per relay rating. When the relay powers up it takes few seconds to complete the selfcheck routing. Ensure Protection Healthy LED (Green) is ON and LED display unit. Wait until the indication goes off. indication appears on the Press or key is displayed Represents MIT 161 relay Press key repeatedly scrolls down the Factory setting Main menu in the following order on the display. - Earth fault is OFF ( is Main menu and is sub menu) - Lowset is OFF 14

15 6. SETTING INSTRUCTIONS 6.1. Select Characteristics FOR EARTH FAULT Pressing key repeatedly get Main menu, press Submenu Key, 3mm LED in the Key Lit to indicate that the Sub menu is activated. Pressing key repeatedly the Sub menu will scroll down in the following order on the display. - Characteristics 1 is in OFF - Definite Time Lag (DTL) By pressing or key choose characteristic (DTL) or OFF and press key. Now the Submenu LED goes OFF and the Main menu appears on the LED display FOR LOWSET Pressing key repeatedly get Main menu, press Submenu Key, 3mm LED in the Key Lit to indicate that the Sub menu is activated. Pressing key repeatedly the Sub menu will scroll down in the following order on the display. - Characteristics 2 is in OFF - Standard Inverse 3 Seconds characteristics. - Standard Inverse 1.3 Seconds. - Very Inverse - Extremely Inverse - Long Time Inverse - Definite Time Lag By pressing or key choose the desired characteristic and press key. Now the Submenu LED goes OFF and the Main menu appears on the LED display Current Settings Setting Range: 0.5% to 25% in steps of 0.5% (For Earth fault and Lowset) EARTH FAULT Pressing key repeatedly get Main menu (represents Earth fault has been set to 10%), press key (Submenu LED On) to get the Sub menu. Pressing the or key, changes the current setting in 5mA increment or decrement. Upon selecting the desired setting, once again press the key (Sub menu LED goes OFF) to return to the main menu. 15

16 LOW SET Pressing key repeatedly get Main menu (represents low set has been set to 10%), press key (Submenu LED On) to get the Sub menu. Pressing or key, changes the current setting in 5mA increments or decrement. Upon selecting the desired setting, once again press the key (Sub menu LED goes OFF) to return to the main menu Time Setting / Time Multiplier setting If characteristic is selected as Definite Time Lag, the Time setting range is, Sec to Sec in steps of 0.01Sec. If characteristic is selected as Inverse curve, the Time Multiplier setting range is to in steps of EARTH FAULT Pressing key repeatedly get Main menu (represents Earth fault Time setting has been set to 3.00sec), press key (Submenu LED On) to get the Sub menu. Pressing the or key, changes the time setting by 0.01sec increment or decrement. Upon selecting the desired setting, once again press the key (Sub menu LED goes OFF) to return to the main menu LOW SET a) For Inverse Characteristics Pressing key repeatedly get Main menu (represents Low set Time Multiplier setting has been set to 1.000), press key (Submenu LED On) to get the Sub menu. Pressing the or key, changes the time setting by increment or decrement. Upon selecting the desired setting, once again press the key (Sub menu LED goes OFF) to return to the main menu. b) For Definite Time Lag Characteristics Pressing key repeatedly get main menu (represents Low set Time setting has been set to 3.00 sec), press key (Submenu LED On) to get the Sub menu. Pressing the or key, changes the time setting by 0.01sec increment or decrement. Upon selecting the desired setting, once again press the key (Sub menu LED goes OFF) to return to the main menu RESET TIME Setting range: 0 sec to 60 sec in steps of 1 sec. (Reset time is common for both Earth fault and Low set) Pressing key repeatedly get Main menu (represents reset time has been chosen as 0 sec). Press key (Submenu LED On) to get Submenu. Pressing the or key, 16

17 changes reset time delay by 1 sec for each pressing. After selecting the desired setting, once again press the key (Sub menu LED goes OFF) to get back the main menu. The recommended setting is 0sec Acceptance of Settings (ENTER) For the relay to accept the above setting changes press X key once, now the display goes off and the settings are updated. By pressing any key again Indication will appear Ensure all the chosen settings. In case of any changes required use Sub menu key and then do the changes and finally press enter X key once. ENSURE TO PRESS X KEY TO ACCEPT THE CHANGES 7. TO CHECK THE RELAY VERSION Press key four times, example of relay version display is as follows: - Represent MIT 161 relay version 1 To get back the main menu, press or key. 8. TO CANCEL SETTING WHILE CHANGING (CANCEL) While the particular setting is being changed (using or key) with Submenu LED ON by pressing X key, the original setting is restored 9. TRIP INDICATION AND RESETTING OF TRIP INDICATION (RESET) When the relay operates, RED " TRIP" LED indicates tripping. By pressing repeatedly the arrow key you will get all trip indication. That is if Earth fault tripped will reappear. Where as if both (Earth fault & Low set) are tripped will appear alternatively for each pressing of the key. Suppose Earth fault has started but not initiated trip, but Low set is tripped then pressing any arrow key (Indicates Earth fault is started) (Indicates Low set is operated) will appear alternatively for each pressing of the key. Once the fault is cleared, press key twice to reset the trip indication. The trip indication and settings will be retained in Non - volatile memory during auxiliary DC power supply failure. 17

18 1. REQUIRED TEST EQUIPMENTS COMMISSIONING 500V insulation test sets. Variable secondary injection current source rated 10A or greater. Time interval meter Primary injection equipment A DC supply with a nominal voltage within the working range of the relays DC auxiliary supply ratings 2. INSPECTION Ensure that all connections are tight and in accordance with the relay wiring diagram and the scheme diagram. Check if the relay is correctly programmed and the relay is fully inserted into the case. 3. APPLYING SETTINGS The relay settings for the particular application should be applied before any secondary testing is started. 4. PRECAUTIONS Before testing commences, the equipment should be isolated from the current transformers and the CTs to be short-circuited, in line with the local site procedures. The tripping and alarm circuits should also be isolated, where practical. Also, ensure that trip links are removed. Ensure that correct DC auxiliary voltage and polarity is applied. See the relevant scheme diagrams for the relay connections. 5. TESTS 5.1. Insulation Connect together all relay CT terminals and measure the insulation resistance between these terminals and all the other relay terminals connected together to earth. Connect together the terminals of the DC auxiliary supply (only +ve and -ve) and measure the insulation resistance between these terminals and all other terminals connected together to earth. 18

19 Connect together all the output relay terminals and measure the insulation resistance between these terminals and all other terminals connected together to earth. A minimum value of 2. 5 to 3 meg ohms can be considered as satisfactory value Secondary injection Select the relay configuration and settings for the application. Note that the MIT relay can be connected either as 1A or 5A-rated device. The user should check this before commencing secondary test. Please refer Sec in installation PICK UP AND RESET The test checks accuracy of the current settings for the relay earth fault characteristics. Apply single-phase current into the current inputs. Slowly increase the current until the starter LED (yellow) operates and record the pick up current in Table 1. Reduce the current until the LED goes off and record this as the reset level. Repeat this test for low set also. Check that all the pick up current levels are measured within 104% ± 4% of the applied setting. Check that the reset levels are 94% of the setting. POLE PICK-UP SETTING MEASURED PICK-UP PICK-UP ERROR MEASURED RESET RESET ERROR E/F LOW SET TABLE IDMTL / DTL CHARACTERISTICS This test checks the accuracy of the main time delay characteristics (IDMTL / DTL). Select the relay current setting characteristics and time multiplier settings as required and then inject a level of current which is a multiple of the relay setting. A time interval meter should be connected to the correct output contact terminals. The timer should be started by the source ON" switch and stopped by the relay trip contacts. Lowset should be selected. A secondary injection timing test circuit is illustrated in Fig. 6. The secondary injection test equipment should be made 'OFF', once the relay contact is closed. 19

20 Table 2 shows theoretical value of each characteristic with time multiplier set to Record the actual results in Table 3 and check that the measured times are within ± 5% or ± 30-m.secs.of theoretical value. CURVE 2 x Is 5 x Is 10 x Is 20 x Is SI SI EI VI LTI DTL * * * * TABLE 2 * USER SETTING Pole LOWSET Characteristic (SI3,SI1,EI, VI LTI,DTL) 2 x Is 5 x Is 10 x Is 20 x Is Delay Error Delay Error Delay Error Delay (±5%) (±5%) (±5%) Error (±5%) TABLE OUTPUT CONTACTS COMBINATION a) Starter - C/O This contact is to be used while testing the pick up and reset value of the relay. b) Common Trip & Alarm for E/F and LOW SET 2 N/O contacts These contacts to be used while testing the E/F & LOWSET characteristics. c) E/F 1 N/O contact This contact to be used while testing the E/F characteristic. 20

21 d) LOWSET - 1 N/O contact This contact to be used while testing the LOWSET characteristic. e) PROTECTION HEALTHY - 1 N/C contact This contact indicates the relay healthiness Primary Injection Primary injection tests are essential to check the ratio and polarity of the transformers as well as the secondary wiring. Ensure the instrument transformer is potential type and isolated from the primary system. Using the circuit shown in Fig.7, check the current transformer ratio and CT phase to earth connection. Inject a current of sufficient magnitude.the secondary current is Is = Primary current / CT ratio 5.4. Putting Into Service After completing all tests satisfactorily, the relay should be put into service as follows: Make a final check of the secondary wiring and tightness of all terminal connections. Insert the DC supply fuse. Check the relay healthy indication/display. Replace the relay cover. Insert the trip links. Perform trip test by secondary injection. Remove all test connections 21

22 Double Pole switch * 240 V A.C SUPPLY A E/F START TIME INTERVAL METER +ve 23 D.C SUPPLY ve STOP 3 4 * Use good quality switch Fig 6 - Secondary injection timing test circuit (Terminals shown are for 1A rating) 22

23 MIT 161 I A E/F I +ve D.C SUPPLY ve PRIMARY INJECTION TEST SOURCE Fig 7 - Primary Injection Test Circuit for E/F Relay (Terminals shown are for 1A rating) 23

24 R Y B AUXILIARY SUPPLY EARTH + VE - VE A 1 1 B (-)Ve (+) Ve MIT Earth 1 23 ALARM CT SHORTING CONTACT TRIP 4 Earth Fault EARTH FAULT CASE TERMINALS VIEWED FROM REAR 16 LOWSET PROTECTION HEALTHY Note : 1. CT Circuit is shown connected to Relay 1A tap. For 5A tap remove 1 1 A wire and connect 1 1 B wire to terminal number 11. Unused current terminal is tightly fixed to a parking rack provided in the terminal block. STARTER 2. Terminal No.23 (Earth) is to be connected directly to Earthbar. MIT161 - WIRING DIAGRAM 24