Motor Protection Device
The multifunction numerical motor protection device provides complete protection of low voltage motors. The device has been developed keeping in view of varied customer needs and various applications of motors. Accordingly, the motor protection device incorporates the following:
- Precise estimate of the thermal image of motor for varying conditions of starting, running, overload, stopping, unbalance conditions. The negative sequence current calculations are taken into account for unbalance current conditions.
- Continuous monitoring of thermal capacity used and in case of power failure the last value of accumulated thermal capacity prior to power interruption is stored.
- Recommendations of ‘’IEEE GUIDE FOR AC MOTOR PROTECTION (STD. C37.96- 2000)’’ and ‘’IEEE GUIDE FOR PRESENTATION OF THERMAL LIMIT CURVES FOR SQUIRREL CAGE INDUCTION MOTORS (STD 620 – 1996)’’
- Six thermal overload curves – 2.5C, 5C, 10C, 15C, 20C and 30C covering the complete range of motor applications.
- Motor start lockout feature inhibiting start of the motor, in case of non-availability of sufficient thermal reserve to complete the acceleration.
- In built Insulation resistance check function prior to start of motor to give a preliminary indication of the condition of insulation, so that the user can take appropriate action for low value of insulation resistance.
- Automatic setting of parameters function, which would set all the protection parameters only on entering the rated full load current as per the motor name plate details.
- Annunciation, in case, the motor fails to stop after the protection device issues trip command.
The salient features of device are:
- LED Seven Segment Display, brighter pixilation and longer life than LCD
- Continuous scanning and display 3 phase currents and thermal capacity used
- Annunciation for each type of fault
- Numerical Algorithm for fast, reliable operation
- Thermal Overload curves selectable as per requirement, Excellent accuracy and long-time stability of thermal curves due to complete software-based implementation
- Customized protection CT as per load requirement supplied with the relay
- Continuous self- supervision and fail-safe operation
- Man-Machine interface through keypad
- Upto five event trip records, FIFO based (with date and time stamping in model – HLEDx)
- Reset Inhibit function, Hour Counter, Online calibration, Password facility (on demand)
- Robust mechanical design and adequate IP 54 degree of protection by enclosure which is shock proof nonmetallic screw less unit
The device provides protection against the following:
- Short Circuit
- Under Current
- Unbalanced current
- Locked Rotor
- Earth Fault
- Single Phasing (Phase Loss)
Following optional protections/ functions are available based on selected variant of MPD:
- Phase reversal
- Over Temperature (Thermistor Based)
- Over Voltage & Under Voltage
- Pre-Trip Alarm for thermal Overload or Definite time overcurrent
- PF, KW & KWH measurement
- Startup Counter with trip facility
- SSR Output for Short Circuit Protection
- Insulation Resistance check facility prior to start of motor
- Data communication over MODBUS RTU protocol between Motor Protection level and higher-level data acquisition for reporting, parameterization, fault annunciation, reset function and hour counter
- 4-20mA Analogue output
- Hour Counter
- Online Calibration
- Password Facility
Rated Current 0.2 to 250 A (Six CT ranges), 50 to 500 A, 100 to 1000 A
Rated Frequency 50 Hz/ 60Hz
Auxiliary Voltage 110 / 230 /415 V AC
Mass of the device 500gms. (approx.)
Mounting type Flush mounted
Dimensions (LxWxD) 96 x 96 x 65 mm
Panel Cutout 92 x 92 mm
CT Range (Based on Motor full load current), Amperes 0.2-6.25, 0.4-12.5, 0.8-25, 2-62.5, 4-125, 40-250,
CT Range (Based on Motor full load current), Amperes 50-500 A, 100-1000 A (in Model – HLEDx)
Line Currents measurement Range 0.2 to 2000A, 50 to 8000A (in Model – HLEDx)
Accuracy +/-1% (0.5 – 1.5 x FLC), +/-5% beyond 1.5 x FLC
Earth Fault Current Measurement Range 1A to 25A, 1A to 100A (in Model – HLEDx)
Accuracy +/- 1% or 1A whichever is greater
Records Stores last five fault records
Hour Meter Records and stores total operational hours
Operation Counter Records and stores number of starts
Thermal Overload curve selection 2.5C, 5C, 10C, 15C, 20C and 30C (six curves)
Thermal Overload setting range 0.2 to 250A, HLEDx – upto 1000 A
Thermal Overload Operating time as per thermal curve selected
Under Current feature Enable/ Disable
Under Current setting range 30% to 80% FLC
Under Current operating time 1 to 60 sec
Locked Rotor setting range As per current range selected, pick up 3 x FLC
Locked Rotor operating time 1 to 10 sec. (in Model – HLEDx)
Locked Rotor pick up delay time (during starting) 1 to 30 sec.
Earth fault feature Enable / disable
Earth fault feature Enable (Residual flux -CBCT used)
Earth fault feature Disable – (Vector summation)
Earth fault setting range 10% to 40% FLC
Earth fault operating time 0.5 sec to 3 sec.
Earth fault pickup delay (during starting) Enable or disable
(When enable; earth fault function will not operate during motor starting for 10 seconds)
Short Circuit setting range As per current range selected, pick up 8xFLC
Short Circuit operating time Instantaneous, 0.1 to 3.0 sec (in Model – HLEDx)
Single phasing setting Enable or Disable
Single phase operating time 2 sec, 1 to 10 Sec (in Model – HLEDx)
Unbalance protection Enable or Disable
Unbalance protection setting range 10% to 40%
Unbalance protection operating time 3 to 10 sec.
Reset Inhibit time 1 to 999 sec.
In eLEDx model below functions are also available:
Low voltage setting range 100 to 500 V
Low voltage operating time 1 to 60 sec.
High voltage setting range 100 to 500 V
High voltage operating time 1 sec (default)
Under load setting range 0.115 to 144 kW
Under load operating time 1 to 60 sec.
Data Output RS 485 MODBUS RTU, Baud Rate–9600, Word length – 8
Analog Output 4-20mA
Dielectric test, IEC 60255- 5 2kV, 50hz, 1 min.
Impulse voltage test, IEC 60255-5 5kV, 1.2/50 Hz microsec., 0.5j
Insulation resistance measurement, IEC 60255-5 > 100 M ohm, 500V DC
Ambient service temperature 0 deg.C to + 55 deg.C
Transport and Storage temperature range 0 deg.C to +70 deg.C
Degree of protection by enclosure, panel mounted IP 54 (Front side of the Device)