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AUGUST 2001

APPLICATION AND COMMISSIONING MANUAL

MIT161 RELAY

EASUN REYROLLE LIMITED

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Issue No : 2nd Issue

Date of Issue : 30.08.2001

Department : TP-CTS

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MIT161 RELAY

SENSITIVE CURRENT PROTECTION

PROTECTION HEALTHY

MIT161

STARTER TRIP

EASUN REYROLLE INDIA

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CONTENTS PAGE

APPLICATION 5

INSTALLATION 12

COMMISSIONING 18

WIRING DIAGRAM 24

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APPLICATION1. INTRODUCTION

The type MIT161 numerical sensitive current protection relay combines the power andflexibility of microprocessor technology. The relay is especially tuned to suit applicationswhere low settings, low burden and rejection of harmonic currents become a necessity.The relay is suitable for high resistance earth fault protection and capacitor bankunbalance 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 providedwith DTL & IDMTL (Standard Inverse 3 sec, Standard Inverse 1.3 sec, Very InverseExtremely Inverse and Long Time Inverse) characteristics.

3. RESET TIME DELAY

The lowset element IDMTL characteristic is also provided with reset time delaycharacteristic for detecting “Flashing faults”.

The increasing use of plastic cables, both, conventionally buried types and aerial bundledconductor types have given rise to the number of "pecking" or "flashing intermittent faultson distribution systems. At the fault position, the plastic melts and temporarily reseals thefaulty cable for a short time, after which the insulation fails again. The same phenomenonhas occurred in joint boxes where an internal flashover temporarily reseals.

The behaviour of different types of over current relays under flashing fault condition iscompared 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 relaywas longer than the time between successive flashes. Early electronic IDMTL relays withinstantaneous reset features were not at all effective in dealing with this condition andonly 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 userprogrammed 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 areincorporated in the protected system, instantaneous resetting is desirable to ensure that, onmultiple shot reclosing schemes, correct grading between the source relays and the relaysassociated with the reclosers is maintained.

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FAULTCURRENT

ELECTROMECHANICALSLOW RESET

STATICINSTANTANEOUS RESET

NUMERICAL (MIT)DELAYED RESET

TRIP

TRIP

TRIP

Fault becomespermanentFlashing Faults

Figure 1 Flashing Fault Protection

4. SYSTEM EARTH FAULT

Distribution Feeder Fault Current magnitude depends upon the amount of fault resistanceand 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 getcomplete protection for line ground fault.

Fig. 2. CT Residual Connection.

Fig.2 shows the CT residual connection for detecting earth faults.

YR B

MIT161

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Fig.3 shows core balance CT connection for sensitive earth fault application.

Fig . 3 CBCT Connection

5. CAPACITOR UNBALANCE CURRENT PROTECTION

MVT161 can be used for unbalanced current protection of double star, delta and single-phase capacitor banks.

INSTALLATION

Fig .4. Double Star Capacitor Bank Neutral Unbalance Protection.

MIT161

YR B

MIT161

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Fig.5. Single phase capacitor bank/ Delta connected bank unbalance protection.

Fig.5. shows single-phase capacitor bank / 3 phase delta connector bank unbalanceprotection. 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 Range24 / 30 / 48 / 110V DC 18 – 135 V DC48/110/220 V DC or 110V AC 43 – 280V 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 0.025 to 1.0 in steps of 0.025Reset Time 0 to 60 sec in steps of 1 sec

MIT161

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6.5. Operating Characteristics

Earth Fault element Definite Time Lag (DTL)

Low set element Standard Inverse 3 sec (SI3)Standard Inverse 1.3 sec (SI1)Very Inverse (VI)Extremely Inverse (EI)Long Time Inverse (LTI) orDefinite Time Lag (DTL)

DTL Operating time 0 to 20.00 sec in steps of 0.01 sec

IDMTL Operating Time can be calculated as follows

K x TMT =

(I/IS) α - 1

Where I – Fault currentIS – Setting currentTM – Time Multiplier Setting

SI3 K = 0.14 α = 0.02SI1 K = 0.0613 α = 0.02VI K = 13.5 α = 1.0EI K = 80.0 α = 2.0LT1 K = 120.0 α = 1.0

6.6. Accuracy

Starter 104% of setting ± 4%Reset ≥ 94% of settingRepeatability ± 1%IDMTL Operate Time ± 5% or ± 35 m.secDTL Operate Time ±1% or ± 35 m.sec.

6.7. Output Contacts

6.7.1. THE RELAY HAS 5 OUTPUT RELAYS

1. Common trip / alarm relay 2 N/O2. Common Starter 1 C/O3. Earth Fault operated 1 N/O4. Low set operated 1 N/O

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5. Protection Unhealthy 1 N/C

6.7.2. CONTACT RATING

Carry continuously 5 A AC rms or DCMake & Carry 20A for 0.2 secBreak 50W DC with a max. of 300V or 5A DC

L/R ≤ 40msec

6.8. Burden

AC (1 Amps) 0.00006VA at 5mA 0.06VA at 250mA

AC (5 Amps) 0.00008VA at 25mA0.2 VA at 1.25A

DC (Quiescent) 5W

7. ENVIRONMENTAL

7.1. Temperature IEC 60068-2-1/2

Operating Range - 10°C to + 55°CStorage Range - 25°C to + 70°C

7.2. Humidity IEC 60068-2-3

4 days at 40°C and 93% RH

7.3. Transient Over voltage IEC 60255-5

5KV, 1.2/50µs, 0.5J between all terminals and Earth or between any two terminalswithout damage or flashover.

7.4. Insulation IEC 60255-5

Variation2.0KV rms for 1 min between all terminals and earth2.0KV rms for 1 min between Independent circuits1.0KV rms for 1 min across normally open contacts

7.5. High Frequency Disturbance IEC 60255–22–1, Class IIIVariation

2.5KV Common (Longitudinal) Mode ≤3%1.0KV series (Transverse) mode ≤3%

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7.6. Electrostatic Discharge IEC 60255-22-2, Class IIIVariation

6KV Contact Discharge ≤5%8KV Air Discharge ≤5%

7.7. Radio Frequency Interference IEC 60255-22-3, Class IIIVariation

20MHz to 1000MHz, 10 V/ m ≤3%

7.8. Fast Transient IEC 60255-22-4, Class IVVariation

4KV, 5/50nS, 2.5KHZ repetitive ≤5%

7.9. Vibration (Sinusoidal) IEC 60255-21-1, Class 1

7.10. Shock and Bump IEC 60255-21-2, Class 1

8. CUTOUT DETAILS

151 x 151mm (2/3 Vedette draw out case)

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INSTALLATION1. UNPACKING

On receipt, remove the relay from the carton box in which it was received and inspect itfor 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 openeduntil 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 originalcarton and stored in a clean dry place.

3. HANDLING

The relay’s electronic circuits are protected from damage by static discharge when therelay is housed in its case. When relay is withdrawn from the case, static handlingprocedures should be observed:

• Before removing the relay from its case the operator must first ensure that he is at thesame 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, thereshould 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 earthwire is connected to the earth strap from the earth terminal 23. Terminal 23 should bedirectly 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 isprovided in one of the four knurling screws fitted on the cover. Sealing can be done usinga sealing wire. Thus mechanical interlock is provided to avoid unauthorized settingchange.

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5. EQUIPMENT

5.1 Current tap Selection

MIT relays are suitable for 1A or 5A application. However the relays are internally wiredfor 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 (IR) of the relay, check the connection of CT wires connectedto the bottom TB (Terminal Block) at the rear of the chassis as per the following table:

For 1A

Terminal No.of TB

Ferrule No. of CTwire(Black)

11 11A

For 5A Terminal No.of TB

Ferrule No. of CTwire(Black)

11 11B

Following are the steps to change the current rating of the relay from 1A to 5A.

1. Identify 11th terminal from number strip on bottom terminal block at the rear of the chassis.

2. The black colour wire “11A” is inserted to 11th 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.11by means of the tool. Insert "11A” wire back to the terminal parking rack.

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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 .

5.2. 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 areGreen colour). First two digits (Red) displays the main menu or type of fault whenselected 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 respectivelyas per relay rating. When the relay powers up it takes few seconds to complete the self-check routing.

Ensure Protection Healthy LED (Green) is ON and indication appears on theLED display unit. Wait until the indication goes off.

Press ↑ or ↓ key is displayed

Represents MIT 161 relay

Press ↓ key repeatedly scrolls down the Factory setting Main menu in the following orderon the display.

- Earth fault is OFF ( is Main menu and is sub menu)

- Lowset is OFF

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6. SETTING INSTRUCTIONS

6.1. Select Characteristics

6.1.1. FOR EARTH FAULT

Pressing ↓key repeatedly get Main menu, press Submenu → Key , 3mmLED 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 thedisplay.

- Characteristics 1 is in OFF- Definite Time Lag (DTL)

By pressing ↑ or ↓ key choose characteristic (DTL) or OFF and press → key. Now theSubmenu LED goes OFF and the Main menu appears on the LED display.

6.1.2. FOR LOWSET

Pressing ↓key repeatedly get Main menu, press Submenu → Key , 3mm LEDin 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 thedisplay.

- 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 theSubmenu LED goes OFF and the Main menu appears on the LED display.

6.2. Current Settings

Setting Range: 0.5% to 25% in steps of 0.5% (For Earth fault and Lowset)

6.2.1. EARTH FAULT

Pressing ↓ key repeatedly get Main menu (represents Earth fault has been set to10%), 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 desiredsetting, once again press the → key (Sub menu LED goes OFF) to return to the mainmenu.

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6.2.2. LOW SET

Pressing ↓ key repeatedly get Main menu (represents low set has been set to10%), 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 desiredsetting, once again press the → key (Sub menu LED goes OFF) to return to the mainmenu.

6.3. Time Setting / Time Multiplier setting

If characteristic is selected as Definite Time Lag, the Time setting range is, 00.00 Sec to20.00 Sec in steps of 0.01Sec.If characteristic is selected as Inverse curve, the Time Multiplier setting range is 0.025 to1.000 in steps of 0.025

6.3.1. EARTH FAULTPressing ↓key repeatedly get Main menu (represents Earth fault Time settinghas been set to 3.00sec), press → key (Submenu LED On) to get the Sub menu. Pressingthe ↑ or ↓ key, changes the time setting by 0.01sec increment or decrement. Uponselecting the desired setting, once again press the → key (Sub menu LED goes OFF) toreturn to the main menu.

6.3.2. LOW SET

a) For Inverse CharacteristicsPressing ↓ key repeatedly get Main menu (represents Low set Time Multipliersetting 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 0.025 increment or decrement. Uponselecting the desired setting, once again press the → key (Sub menu LED goes OFF) toreturn to the main menu.

b) For Definite Time Lag CharacteristicsPressing ↓ key repeatedly get main menu (represents Low set Time setting hasbeen 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 selectingthe desired setting, once again press the → key (Sub menu LED goes OFF) to return to themain menu.

6.3.3. 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 chosenas 0 sec). Press → key (Submenu LED On) to get Submenu. Pressing the ↑ or ↓ key,

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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.

6.4. Acceptance of Settings (ENTER)

For the relay to accept the above setting changes press X key once, now the display goesoff 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 thendo 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 1To 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 faulttripped 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 pressingany arrow key (Indicates Earth fault is started) (Indicates Low set isoperated) 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 auxiliaryDC power supply failure.

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COMMISSIONING1. REQUIRED TEST EQUIPMENTS

• 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 andthe scheme diagram. Check if the relay is correctly programmed and the relay is fullyinserted into the case.

3. APPLYING SETTINGS

The relay settings for the particular application should be applied before any secondarytesting is started. 4. PRECAUTIONS

Before testing commences, the equipment should be isolated from the currenttransformers and the CTs to be short-circuited, in line with the local site procedures. Thetripping and alarm circuits should also be isolated, where practical. Also, ensure that triplinks are removed.

Ensure that correct DC auxiliary voltage and polarity is applied. See the relevant schemediagrams for the relay connections.

5. TESTS

5.1. Insulation

Connect together all relay CT terminals and measure the insulation resistance betweenthese 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 measurethe insulation resistance between these terminals and all other terminals connectedtogether to earth.

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Connect together all the output relay terminals and measure the insulation resistancebetween 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.

5.2. Secondary injection

Select the relay configuration and settings for the application. Note that the MIT relay canbe connected either as 1A or 5A-rated device. The user should check this beforecommencing secondary test. Please refer Sec. 2.1. in installation

5.2.1. 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 thestarter LED (yellow) operates and record the pick up current in Table 1. Reduce thecurrent until the LED goes off and record this as the reset level. Repeat this test for low setalso.

Check that all the pick up current levels are measured within 104% ± 4% of the appliedsetting. Check that the reset levels are ≥ 94% of the setting.

POLE PICK-UPSETTING

MEASUREDPICK-UP

PICK-UPERROR

MEASUREDRESET

RESETERROR

E/F

LOW SET TABLE 1

5.2.2. 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 andthen 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. Thetimer 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 isclosed.

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Table 2 shows theoretical value of each characteristic with time multiplier set to 1.000.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 3 10.03 4.28 2.97 2.27

SI 1 4.39 1.87 1.3 1.0

EI 26.67 3.33 0.81 0.20

VI 13.50 3.38 1.50 0.71

LTI 120.00 30.0 13.33 6.32

DTL * * * *

TABLE 2 * USER SETTING

2 x Is 5 x Is 10 x Is 20 x IsPole Characteristic(SI3,SI1,EI,VI LTI,DTL)

Delay Error(±5%)

Delay Error(±5%)

Delay Error(±5%)

Delay Error(±5%)

LOWSET

TABLE 3

5.2.3. 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.

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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.

5.3. Primary Injection

Primary injection tests are essential to check the ratio and polarity of the transformers aswell 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 earthconnection. 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

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* Use good quality switch

Fig 6 - Secondary injection timing test circuit (Terminals shown are for 1A rating)

A

TIMEINTERVALMETER

START

STOP

240 VA.CSUPPLY

+ve -veD.C SUPPLY

E/F

11 12

22 24

3 4

23

Double Pole switch *

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Fig 7 - Primary Injection Test Circuit for E/F Relay(Terminals shown are for 1A rating)

+ve -veD.C SUPPLY

E/F

A

PRIMARY INJECTION TEST SOURCE

MIT 161

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