SWITCHGEAR S AF E & S UR E
Motor Protection Relay
MPR300
MPR300 • •
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Compact Microcontroller based design 6 models to cover motor rated currents upt o 88A 5 protections 3 integral Cts DIP switch selection for Thermal Characteristics Trip indication Test funct ion
Applications MPR 300 Motor protection relay is suitable for back panel surface mounting or DIN rail mounting. It offers multiple protections to 3 phase induction motors. The R-Y-B phase wires of the motor passes through the relay (no need for external Cts). The measurements are carried out through integral CTs and electronics built inside the relay. One set of trip contacts (1 N/O + 1 N/C) is available for trip functions along with individual LED indications. The relay is ideally suitable for protection of motors coupled to pumps, compressors, fans, ventilators, cranes, elevators, escalators, saw mills, paper mills, motorized valves, conveyor belts etc. where frequent over loads, rotor stalling, faulty bearings, and dry running conditions are expected.
PROTECTIONS a) b) c) d) e)
Thermal over load protection : Negative sequence protection Earth Fault protection Locked rotor protection Under current protection
Each of the above faults are indicated by a LED on the front panel. On occurrence of fault, the relay provides two contacts 1 N/O and 1 N/C. These contacts are manual reset and can be used to open a contactor. The LED fault indication is manual reset on clearance of the fault, the LED has to be reset by the front panel Reset PB.
TECHNOLOGY MPR 300 uses state of the art digital technology to measure the three phase and residual currents in the motor feeder. The current signals are sensed through inbuilt CTs and evaluated by microcontroller using advanced digital sampling techniques. Special algorithms are used for deriving the thermal status and other parameters required for various protections. The hardware design provides high degree of accuracy and reliability. The relay comes in 6 different models to cover full range of motor rated currents starting from 1A to 88A. In addition to offering important protections, the relay is most user friendly, simple to withstand high level of EMI/EMC interferences which are increasingly present in the present day industrial environment.
TECHNICAL SPECIFICATIONS Input Connection Basic Protections
R-Y-B wires of motor passes through relay Thermal Over load, Negative Sequence (Phase Unbalance) Locked Rotor, Earth Fault and Under Current
Thermal Over Load Protecti on 1.
2. 3. 4.
Current setting 1 to 88A in 6 different models as follow s : 1 to 2.75A 2 to 5.50A 4 to 11A 8 to 22A 16 to 44A 32 to 88A Trip Time Characteristics Class 10A, 10, 20 and 30 as per LEC 947-4-1 Field selectable through front DIP switches. Pre alarmAt 1.05 lm by flashing LED (lm = Motor rated current) Thermal MemoryProvided. TRIP CLASS 10A 10 20 30
Tripping Time at multiple of Ie 120% > 2 hours > 2 hours > 2 hours > 2 hours
150% 2min 4min 6min 12min
720% 2-10 sec. 4-10 sec. 6-20 sec. 9-30 sec.
Earth Fault Protecti on 1. 2. 3.
Current setting 10 to 50% of Im field selectable by front panel pot. Trip time delay 200 msec factory set Disable feature Available from front panel pot.
Phase Unbalance Protecti on 1. Unbalance current 50% of Im factory set 2. Trip time delay 3 sec factory set Locked Rotor Protection 1. 2. 3.
Locked rotor current3 Im factory set Trip time delay 1sec factory set Disable featureAvailable from front panel DIP switch
Under Current Protection 1. Under current threshold50% of Im factory set 2. Trip time delay3 sec factory set 3. Disable featureAvailable from front panel DIP switch Operation al Indicators LED indications for Power On LED indications for trip on each of the 5 faults LED starts flashing when fault is detected. Becomes steady on When the relay trips after the preset time delay. LEDs are manual reset. Contacts
1 N/O + 1 N/C manual reset Rated Voltage – 250 V AC / 30 V DC Rated Current 5A Rated breaking capacity 2000 VA / 240 W (resistive)
Au xi li ary Po wer Su pp ly
240 V AC +/- 20%
Operating Temperature Ac cu rac y Reset Current Reset Time
0 to 60 degrees C As per IEC 947-4-1 95% to 90% of Im Less than 160 millisec for O/L, N/S, U/C and L/R faults Less than 80 milisec for Earth fault IEC 60255, IEC 61000 and IEC 60068
Reference Standards
Wiring Diagram for MPR300
LARSEN & TOUBRO LIMITED Powai Works, Saki Vihar Road, P.O. Box 8901 Mumbai 400 072
