Sepam - HV/MV Protection and control units (ENG) - Trinet

Earth fault (50N/51N)Protection against earth faults. The following typesof time delay settings are available: definite, standardinverse, very inverse, extremely inverse and ultrainverse.Earth fault current detection can be provided by:v three phase current transformers,v a current transformer (1 A, 5 A), combined witha CSH30 interposing ring CT,v a CSH120 or CSH200 core balance CT, accordingto the required diameter, this method being the mostaccurate one.The two ratings available (2 A and 30 A) providea very wide setting range,Directional earth fault (67N)This protection has several uses:v highly sensitive earth fault protection of transformerfeeders supplied by long cables characterized by highcapacitive current,v quick, selective detection of upstream earth faultswhen there are several incomers in parallel.Overvoltage (59)Protection against abnormally high voltage andchecking that there is sufficient voltage of powersupply changeover. This protection monitors systemvoltage U21.Neutral voltage displacement (59N)Detection of insulation faults in ungrounded systemsby measurement of neutral voltage displacement.This protection is generally used for transformerincomers or busbars.Undercurrent (37)Pump protection against the consequences of primingloss. This protection detects delayed undercurrentcorresponding to motor no-load operation which istypical of a loss of pump priming.Underfrequency (81L)Detection of variances with respect to the rated frequency, in order to maintainhigh quality power supply. This protection can be used for overall tripping or forload shedding.Overfrequency (81H)Protection against abnormally high frequency.Undervoltage (27)Protection used either for automated functions (changeover, load shedding)or for the protection of several motors against undervoltage. This protection checksfor undervoltage in each of the phase-to-phase voltages measured.Positive sequence undervoltage (27D)Protection of several motors against malfunctioning due to insufficientor unbalanced supply voltage.Remanent undervoltage (27R)Monitoring of the clearing of voltage sustained by rotating machines after theopening of the circuit. This protection is used with automatic changeover functionsto prevent transient electrical and mechanical phenomena that are caused by fastresupply of power to motors. It monitors system voltage U21.Neutral (50N/51N)Overload protection of neutral earthing impedance and sensitive overall networkprotection against earth faults. This “earth fault” protection is associated witha current sensor installed on the neutral earthing connection.Reactive overpower (32Q/40)Protection of synchronous drives against field loss which causes overconsumptionof reactive power and leads to the loss of synchronism.Reverse real power (32P)Protection of motors against operation as generators when driven by their loads or,in the case of double sources, to avoid the output of one source into the other.It is based on the real overpower function F531.Direction of rotation (47)Protection which prevents the changing of direction of motor rotation followinga power supply modification.Temperature monitoring (38/49T)Protection which detects abnormal overheating of equipment fittedwith Pt100 type platinum resistor type temperature sensors.v 1 alarm setting,v 1 tripping setting.The cabling of each sensor is continuously monitored.Voltage restrained overcurrent (51V)Three-phase protection against alternator phase faults. Its characteristics aresuitable for the weak current suppied by the alternator when a short-circuit occurs.Synchro-check (25)Closing of the breaking device if the two circuits have voltage, frequency or phasevariances within the planned limits.Restricted earth fault (64 REF)Detection of phase to earth faults in the winding of the transformer connected tothe secondary end of the protection. This protection may be used when thesecondary neutral is earthed inside the protected zone.Installation - Use - General characteristics - Testing2/13