I-Gard MGFR Series, Instruction Manual

Page 1: ...C 322EM Instruction Manual March 2015 GROUND FAULT RELAY GROUND FAULT RELAY MGFR ...

Page 2: ...omer service and technical leadership We build on this foundation by investing in developing new products in electrical safety education including EFC scholarship program by actively participating in the IEEE community programs on technical and electrical safety standard and working with local universities at discovering new technologies We remain unrelenting in our goal of improving electrical sa...

Page 3: ... Capacity 11 5 10 Transient Immunity 11 5 11 Relay Contacts 11 5 12 Dropout to Pick up Ratio 11 5 13 Frequency Range 11 5 14 Standards except AB types 11 6 Installation 12 6 1 Site Requirements 12 6 2 Mounting 12 7 Maintenance 12 7 1 General 12 7 2 Troubleshooting 14 TABLE OF FIGURES Figure 1 Block Diagram of MGFR Relays 15 Figure 2 Time Current Characteristics 16 Figure 3 Time Current Characteris...

Page 4: ...d relays which measure the ground fault current from the secondary of a zero sequence current sensor connected to the relay Upon a ground fault the relay computes the RMS value of the fault current If the fault current is above the level of pick up setting of the relay the trip unit operates to open a circuit breaker in accordance with a set of programmable time current characteristics The series ...

Page 5: ...tch on the front panel of the relay The switch is located under the heading PICK UP within the SETTING section on the faceplate Once the red cursor of the switch is set at any of the eight positions the figure in between the two black lines pointed by the middle line of the red cursor indicates the desired pick up setting 2 3 TIME CURRENT CHARACTERISTICS Except in MGFR 1 ZB MGFR 1 AB and MGFR SE Z...

Page 6: ...rip time is definite and matches with the DMT settings of a specific relay as shown in section 2 3 1 Both sets of IDMT curves have similar mathematical representations as shown in Eqn 1 but the relay constants are different to match different minimum operating times The IDMT and DMT characteristics applicable to MGFR 1 ZB MGFR 2 ZB MGFR 20 ZB MGFR 1 AB MGFR 2 AB MGFR 20 AB are shown in Figure 2 Th...

Page 7: ...y is taken from the line side of breaker or from UPS the target can be manually reset by a momentary push button on the faceplate The relay itself is also reset on power up 2 5 2 ALL OTHER MODELS OF MGFR All the relays have a red LED light for trip indication which is manually reset by a momentary push button on the faceplate The button function will be explained in detail in the next section If t...

Page 8: ...developing fault However this value is user programmable by the same pushbutton The values of fault current at which the flashing can start to occur are 0 16 0 25 0 75 and 0 90 of pick up After pressing and releasing the switch for the first time the last fault current value will appear on the display Pressing the switch again after an interval of 1 1 5 seconds and releasing it will cause the numb...

Page 9: ...perated a TEST current will flow in the relay for the duration as set by the time setting switch The value of the current will show in the display in per unit for a few seconds after the relay has tripped The relay knows that this is a TEST current and not a FAULT current So this value will not be stored in the memory The breaker will trip and the trip target will come up If R3 and R4 terminals ar...

Page 10: ...number of levels Also a number of downstream relays can be connected to restrain a single main relay or more if necessary Three terminals are provided on each relay ZSIP IN ZSIP OUT and COMMON The COMMON is connected to all other COMMON terminals in the system The ZSIP OUT of all downstream relays at a particular level is connected to the ZSIP IN of the relay at the next level up All wiring is by ...

Page 11: ...he neutral of a 3 phase 4 wire power system pass through the window of a zero sequence sensor described in section 3 The secondary of the sensor is connected to X and XI W1 and W2 in case MGFR SE ZB terminals of the relay Analog current signals from the sensor are converted to proportional voltage outputs and digitized by an A D converter in the relay The microprocessor collects the digital sample...

Page 12: ...ifications provided in this section cover all models of the MGFR series unless stated otherwise 5 2 CONTROL POWER ZB 120 60 Hz 15VA AB 240 50 Hz 9VA 5 2 1 OPERATING VOLTAGE TOLERANCE ZB AB Max Voltage 130 265 V AC Min Voltage 65 130 V AC 5 3 TEMPERATURE RANGE Operating Ambient Temperature 0 C to 70 C Storage Temperature 20 C to 85 C Continuous operation at maximum operating temperature is not reco...

Page 13: ... MGFR 200 AB MGFR 1200 ZB MGFR 1200 AB MGFR SE ZB 50 KA for 1 sec 5 10 TRANSIENT IMMUNITY According to ANSI IEEE C62 41 1980 and ANSI IEEE C37 90 1978 5 11 RELAY CONTACTS 5 11 1 TRIP CONTACT One Form C SPDT dry contact rated 10 A at 240V AC or 24 V DC resistive 5 11 2 PRE TRIP ALARM CONTACT One Form A SPST Normally open dry contact rated 0 3 A 120V AC or 0 5A 24V DC 5 12 DROPOUT TO PICK UP RATIO 0...

Page 14: ... This is shown in Fig 7 First remove the C shaped mounting bracket from the back of the MGFR install the MGFR on to the relaying compartment door from the front and through the cut out refasten the mounting bracket on to the MGFR with the two No 6 32 retained screws provided Tighten the screws so that the relay sits flush with the compartment door When the unit is in position and powered up the di...

Page 15: ...cuit breaker to trip in response to a fault may be caused by any of the reasons below a Relay set too high Check that the pick up settings on the relay are correct b Supply not grounded or neutral grounded on the downstream side of the main sensor c ZSCT improperly connected Check that all connections are tight wiring is correct and leads are not broken Any current sensor with an open circuited se...

Page 16: ...re are various ways to suppress any counter EMF that might occur The methods vary depending on applications types of breaker used etc Contact I Gard if necessary 7 2 7 UNIT TRIPS INSTANTANEOUSLY The MGFR will trip Instantaneously without Time Delay if the Factory supplied jumper is missing from the ZSIP OUT and ZSIP IN terminals at the rear of the unit 7 2 8 MAIN RELAY TRIPS The system has a main ...

Page 17: ...FIGURE 1 BLOCK DIAGRAM OF MGFR RELAYS ...

Page 18: ...TIME CURRENT CHARACTERISTICS FOR MGFR 1 ZB MGFR 2 ZB AND MGFR 20 ZB MGFR 1 AB MGFR 2 AB AND MGFR 20 AB FIGURE 2 TIME CURRENT CHARACTERISTICS ...

Page 19: ...TIME CURRENT CHARACTERISTICS FOR MGFR 200 ZB MGFR 1200 ZB AND MGFR SE ZB MGFR 200 AB AND MGFR 1200 AB FIGURE 3 TIME CURRENT CHARACTERISTICS ...

Page 20: ...FIGURE 4 3 LEVEL TCP AND ZSIP CONNECTION ZONE SELECTIVE INSTANTANEOUS PROTECTION ZSIP TIME CO ORDINATED PROTECCTION TCP ...

Page 21: ...FIGURE 5 CONNECTION DIAGRAM FOR MGFR RELAYS ...

Page 22: ...FIGURE 6 CONNECTION DIAGRAM FOR MGFR SE ZB RELAYS ...

Page 23: ...FIGURE 7 OUTLINE MOUNTING DIMENSIONS FOR MGFR RELAYS FIGURE 8 RECOMMENDED DIODE PROTECTION TO REDUCE SWITCHING SPIKES ...

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