ABB REL650 Product Manual

Also see for REL650 series: Technical manual Product guide Product guide Technical manual Commissioning manual

Contents

ABB REL650 Product Manual Manual pdf 21 page image

sequence source is weak or open, the forward source impedanceis strong and it is desired to detect forward ground faults.Additionally, it is applied in applications on cables, where zerosequence impedance depends on the fault current return paths,but the cable negative sequence impedance is practicallyconstant.The directional function is current and voltage polarized. Thefunction can be set to forward, reverse or non-directionalindependently for each step. Both steps are provided with asettable definite time delay.DNSPTOC (46) protects against all unbalanced faults includingphase-to-phase faults. The minimum pickup current of thefunction must be set to above the normal system unbalance levelin order to avoid inadvertent tripping.6. Voltage protectionTwo step undervoltage protection UV2PTUV (27)Undervoltages can occur in the power system during faults orabnormal conditions. Two step undervoltage protection(UV2PTUV, 27) function can be used to open circuit breakers toprepare for system restoration at power outages or as long-timedelayed back-up to primary protection.UV2PTUV (27) has two voltage steps, where step 1 is settable asinverse or definite time delayed. Step 2 is always definite timedelayed.UV2PTUV (27) has a high reset ratio to allow settings close tosystem service voltage.Two step overvoltage protection OV2PTOV (59)Overvoltages may occur in the power system during abnormalconditions such as sudden power loss, tap changer regulatingfailures, and open line ends on long lines.Two step overvoltage protection (OV2PTOV, 59) function can beused to detect open line ends, normally then combined with adirectional reactive over-power function to supervise the systemvoltage. When triggered, the function will cause an alarm, switchin reactors, or switch out capacitor banks.OV2PTOV (59) has two voltage steps, where step 1 can be set asinverse or definite time delayed. Step 2 is always definite timedelayed.OV2PTOV (59) has a high reset ratio to allow settings close tosystem service voltage.Two step residual overvoltage protection ROV2PTOV (59N)Residual voltages may occur in the power system during groundfaults.Two step residual overvoltage protection ROV2PTOV (59N)function calculates the residual voltage from the three-phasevoltage input transformers or measures it from a single voltageinput transformer fed from a broken delta or neutral point voltagetransformer.ROV2PTOV (59N) has two voltage steps, where step 1 can be setas inverse or definite time delayed. Step 2 is always definite timedelayed.Loss of voltage check LOVPTUV (27)Loss of voltage check LOVPTUV (27) is suitable for use innetworks with an automatic system restoration function.LOVPTUV (27) issues a three-pole trip command to the circuitbreaker, if all three phase voltages fall below the set value for atime longer than the set time and the circuit breaker remainsclosed.The operation of LOVPTUV (27) is supervised by the fuse failuresupervision SDDRFUF.7. Frequency protectionUnderfrequency protection SAPTUF (81)Underfrequency occurs as a result of a lack of sufficientgeneration in the network.Underfrequency protection SAPTUF (81) measures frequencywith high accuracy, and is used for load shedding systems,remedial action schemes, gas turbine startup and so on.Separate definite time delays are provided for operate andrestore.SAPTUF (81) is provided with undervoltage blocking.Overfrequency protection SAPTOF (81)Overfrequency protection function SAPTOF (81) is applicable inall situations, where reliable detection of high fundamental powersystem frequency is needed.Overfrequency occurs because of sudden load drops or shuntfaults in the power network. Close to the generating plant,generator governor problems can also cause over frequency.SAPTOF (81) measures frequency with high accuracy, and is usedmainly for generation shedding and remedial action schemes. It isalso used as a frequency stage initiating load restoring. A definitetime delay is provided for operate.SAPTOF (81) is provided with an undervoltage blocking.Rate-of-change frequency protection SAPFRC (81)The rate-of-change frequency protection function SAPFRC (81)gives an early indication of a main disturbance in the system.Line distance protection REL650 ANSI 1MRK 506 337-BUS BProduct version: 1.3ABB 21