TMSS STANDARDPROTECTION RELAY Thermal Current Rating of the RelayFault Current RangeDuration

4InContinuous

30InFor 10s

100InFor 1s

NGSA Standard And Basic Range Of RelayRelay CodeApplicationStandard

Min Operating TimeRangeStandard

50/51Non-Dir O/C20msHigh Set0.01-4In(0.01)Low Set 1-40 In(0.05)IEC 60255-151 2009DMT/IDMT

50/51NNon-Dir E/F20msHS 0.1-2 In(0.01)LS(0.1-20 In (0.01)IEC 60255-151 2009DMT/IDMT

67Dir 3 O/C20msHigh Set0.01-4In(0.01)Low Set 1-40 In(0.05)RCA(-600 TO +600)IEC 60255-151 2009DMT/IDMT

27/59 & 59NUV/OV-0.05-1.2 Vn (0.01)IEC 60255-127: 2010

81OF/UF-0.9-1.2 Fn (0.001)-

51BF / 51NBFCBF/BFP-0.1-2 In (0.01)-

87LLin. Diff-0.05 2 In (0.01)IEC 60255-121:2014

21/21NDistanceOne Cycle (Z1)X/R 30IEC 60255-121:2014

87TTraf-Diff20ms @ 200% Pick Up Current0.05-2 In(0.01)IEC 60255-13 : 1980

64REFREF20ms0.01-2 In (0.01)IEC 60255-13 : 1980

87BLow Impedance BB-Dif-0.01-2 In (0.01)-

87BHigh Impedance BB-Dif-0.01-2 In (0.01)-

Operation FunctionCodeProtectionOperation Function

37Under Current Under current protection operating disappearing or sinking Current Flow This may be happened by switching operation and or by falling loads or supply

46Phase Unbalance This Protection shall detect the unbalance currents with two levels start and operate The phase unbalance protection function shall be able to detect the unsymmetrical feeder Voltages

51BF/51NBFBreaker Failure Protection The circuit breaker Failure protection shall be initiated by trip signal from any protection function. The initiation signal can be external through binary input or internally. Where single pole tripping is applied, the breaker Failure protection shall be phase segregated.

87LLine Differential The fibre optic core shall be provided for communication. An extra redundant full duplex 2.0 Mbit/Sec Channels shall be provided for unit protection which shall essentially be synchronized through the GPS system and inter tripping through the telecom network

21/21NDistance It shall be provided with 5 distance zones and selectable Quadrature and Mho characteristics and shall have independent zone reach setting. Each zone shall be adjustable for forward or reverse looking The protection shall support parallel line and load current compensation features Single phase, sensitive, for directional comparison earth fault protection for high resistance ground faults using permissive scheme using tele protection scheme via fibre optics, with echo back feature for open end line and weak in feed and permissive over reach features SOTF feature shall initiate 3-phase instantaneous tripping and block the auto reclosing relay The distance protection shall be provided with VT fuse failure blocking internally or via binary input signal Power swing blocking scheme provided and it shall be quadrilateral The ground fault protection of all zones shall be provided with residual compensation or both positive and zero sequence resistance and reactance independently settable for each zones The operating time of zone-1 protection shall not be unduly increased due to CVT transients. The transient performance CVT as per IEC 61869-5: 2011 shall provide protection stability & security for close-in faults in both directions.

79Auto Reclose This function only applicable for overhead lines/feeders, it shall be blocked for underground cable line/feeders The thermal overload and switch on to fault protection function shall be settable to block the auto reclosing function if operated and unblock AR function when resettled The three pole AR function shall be released by a syncrochek signal internally from incorporated synchrochek function or externally via binary input signal

87TTrafo Diff

The distance protection scheme shall include but not limited to the following additional functions/features as shown in tableAddition Features of distance protectionNoAddition Features

1It shall be provided with sensitive directional earth fault function for high resistive fault

2Switch on to fault features external triggering(SOTF)

3Voltage circuit supervision

4Power Swing blocking function(with selectable zones)

5Out of step tripping function for facilitating islanding I case of requirement

Inter Tripping scheme in Distance ProtectionNoInter Tripping Schemes

1Permissive Under reach scheme

2Permissive Over reach scheme

3Overreach Blocking scheme

4Zone-1 Extension Scheme

5Basic 3-zone distance

6Weak-In-Feed and echo back feature

Condition of Auto recloser to lockout the CBNoCase or Condition for lockout of CB closing

1Unsuccessful Auto reclosing

2Close time out and the Circuit Breaker did not close

3A new shot is initiated during the discrimination time

4The protection trip signal has been active longer than the dead time

Charging Current Calculation!Charging current Ic = 2 x pi x f x C x V

Where f is the frequency of the supply C is the Capacitance of the line V is the voltage of the line

DISTANCE PORTECTION The use of the overreaching scheme will improve the resistive coverage 3