DescriptionThe MJT 314 B (Self powered numerical overcurrent protection)

& MJT 314 C (Self powered with series trip numerical overcurrent

protection) relay combines the power and flexibility of

microprocessor technology with decades of experience in the

field of protection. A wide range of protection elements and

characteristics are supplemented by advance features such as

metering, fault recorder and communication.

MJT 314 (B&C) offers inverse time and definite time over current

protection for phase fault and earth fault with communication.

DesignThe MJT Protection unit consists of the following modules within

its dimensions.

• Input Module

• Power Supply and Output Relay module

• Measuring Module & communication interface

• Front Fascia

• Status input module

The four modules viz. Input, Power supply, Measuring and status

input modules are plugged into the Front fascia which houses

switches, LEDs and LCD display for the human machine

interface. All PCB s are well protected from one another and from

external environment with best shielding for better

electromagnetic compatibility and housed in the enclosed

chassis, which is withdrawable from the outer case.

The draw-out case is provided with the required CT shorting

contacts.

Applications• Distribution feeders

• Transmission lines

• AC machines

• Capacitor banks

• Transformers

• Used in Compact MV Switch Boards with CB

• Where Auxillary Voltage is not available or guaranteed

Genesis Range

MJT 314 B&C

e3

Ele

gant

Easy to Use

Efficient

Numerical Self PoweredOvercurrent & EarthfaultProtection

Key Features of MJT 314 B(Self Powered Numerical Over Current Protection)

• Charged capacitor output is available to actuate low energy

magnetic actuator in the Breaker(12-24V DC output-

0.25 joules)

• In absence of low energy magnetic actuator, the breaker

can be tripped using power from external power pack. For

the same one N/O contact is available in the relay

Key Features of MJT 314 C(Self Powered with Series Trip Numerical Over Current

Protection)

• This relay comes with two boxes, One with main Relay and

other with series Trip element .

• Output of the main relay has been modified suitably to

energize, special B33 type of series trip element three

numbers(coils are connected in series). The break contacts

of this will be used to divert the C.T current to the series

trip coils of the breaker.

Numerical Overcurrent &Earthfault Protection - MJT 314 (B&C)

Common Features for MJT 314

(B&C)

• Two group settings

• Storage of two fault records

• Internal real time clock

• Suitable for flashing faults

• Gets power from the C.T input itself. (No auxiliary D.C

supply necessary)

• The current measurement on relay is available when current

flows more than 400mA on all the three phases

• The Back light of the LCD will glow when current flows

more than 750mA

• To set the relay or read the fault records (in absence of

current input ) a separate battery box with inbuilt battery

charger is available, external to the relay. (order to be placed

separately for this)

• Wide range of current settings

• Self diagnostics feature

• Currents-Ir,Iy,Ib,Ie

• Readable human machine interface with Backlit LCD

display

• LED indications

• Push buttons for viewing/editing the settings and resetting

• Data communication using IEC 60870-5-103 Protocol

• RS485 communication electrical terminals at rear

Protection• IDMTL / DTL phase fault overcurrent ( 50 / 51 )

• IDMTL / DTL earth fault overcurrent ( 50N /51N)

• Dual DC transient free highsets for phase fault & earth fault

• True RMS measurement

• Six characteristics

ControlThe relay has the following output contacts

MJT 314 B

• Normally Open 1 N/O

• Capacitor Charged Outputs 1 N/O

MJT 314 C

• Capacitor Charged Outputs 1 N/O

Typical Wiring Diagram for MJT314 B

Typical Wiring Diagram for MJT314 C

Wiring Diagrams

Technical InformationCT Input Rating 1A & 5A

Frequency 50Hz

Auxiliary Supply

Self Powered from CT input

Protection Settings

Phase Fault 0.5xIn to 2xIn Δ 0.01 In

Earth Fault 0.2xIn to 0.8xIn Δ 0.01 In

Highset1 Phase Fault 4xIn to 20xIn Δ 0.5 In, off

Highset1 Earth Fault 0.5xIn to 12xIn Δ 0.5 In, off

Highset2 Phase Fault 4xIn to 20xIn Δ 0.5 In, off

Highset2 Earth Fault 0.5xIn to 12xIn Δ 0.5 In, off

P/F Time Multiplier 0.025 to 1.6 Δ 0.001

E/F Time Multiplier 0.025 to 1.6 Δ 0.001

P/F DTL 0 Secs to 20 Secs Δ 0.01 Secs

E/F DTL 0 Secs to 20 Secs Δ 0.01 Secs

P/F Highset1 DTL 0 Secs to 20 Secs Δ 0.01 Secs

E/F Highset1 DTL 0 Secs to 20 Secs Δ 0.01 Secs

Highset2 Instantaneous

Reset Time 0 to 60 Secs Δ 1 sec

Inverse Characteristics

Operating time can be calculated as follows:

where

I=fault current

Is=current setting

Tm=time multiplier

Si3 - k =0.14, a= 0.02

SI1 - k =0.0613, a= 0.02

VI - k =13.5, a= 1.0

EI - k =80.0, a= 2.0

LTI - k =120.0, a= 1.0

Contact Rating

Carry continuously 5A AC rms or DC

Make & Carry 20A for 0.2sec

Break Resistive 75W DC

Inductive 50W DC

@L/R#40msec

with a maximum of 300V DC

Resistive 1250 VA AC

Inductive 250 VA @ PF #0.4

Indication

Green LED Protection healthy

Orange LED Starter

Red LED Trip

Red LED (3mm) Submenu

16x2 Alphanumeric LCD display for settings, metering and fault

data

Burden

AC Current Input

5 A Rating #15 VA

1 A Rating #3 VA

Auxiliary input

Quiescent (typical) 5 W (DC)

12VA (AC)

Environmental

Temperature IEC 60068-2-1/2

Operating range -10° C to +55°C

Storage range -25° C to +70°C

Humidity IEC 60068-2-3

4 days at 40°C and 93%RH

Transient Overvoltage IEC 60255-5

5KV, 1.2/50Fs, 0.5J between all terminals and earth or between

any two terminals without damage or flashover

Insulation IEC 60255-5

2.0 KVrms for 1 min between all terminals and earth

2.0 KVrms for 1 min between independent circuits

1.0 KVrms for 1 min across normally open contacts

High frequency Disturbance IEC 60255-22-1 Class III

2.5 KV Common (Longitudinal) mode #3%

1.0 KV Series (Transverse) mode #3%

Electrostatic Discharge IEC 60255-22 -2 Class III

6 KV Contact Discharge #5%

8 KV Air Discharge #5%

Radio Frequency Interference IEC 60255-22-3 Class III

20 MHz to 1000 MHz, 10V/m #3%

Fast Transient

2 KV, 5/50 ns, 2.5 kHz repetitive IEC 60255-22-4 Class III #3%

Vibration (Sinusoidal) IEC 60255-21-1 Class I

Shock and Bump IEC 60255-21-2 Class I

Mechanical Classification6Durability in excess of 10 operations

The policy of EASUN REYROLLE is one of continuous improvement and development. The company therefore reserves the right to supply equipment which may differ slightly

from that described and illustrated in the publication.

ERL

ERL Group Corporate Office#389, “Rasukumaki”, Hulimavu, Begur Hobli, Bannerghatta Road, Bangalore – 560 076, IndiaTel: +91 80 6717 7000 / 7001 Fax: +91 80 6717 7002 Email: cenmarket@easunreyrolle.net

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www.easunreyrolle.com

MODULAR CASES: SIZES 6

SIZE 6 CASE

A B C

155 151 130.5

Note:1. All dimensions are in mm2. All dimensions are measured equidistant from centre line3. Maximum depth of equipment inside panel : 200mm

Ordering InformationBattery sourceMJT 314 B or MJT 314 CCT Rating 1 Amp or 5 Amps

QualificationISO 9001-2008

Cutout Details