The 7SV600 is a numerical relay used for circuit breaker failure protection. This condition is when the circuit breaker fails to correctly open and clear the fault after single- or three-pole trip commands have been issued by the protection. It is then necessary to trip the relevant bus-bar zone (section) to ensure fault clearance. Generally, the monitoring of the current suffices as the criteria for the indication that the circuit breaker has successfully cleared the fault ("current condition"). However, under certain fault conditions, (e.g. overvoltage) little or no current may flow making the measurement of current unreliable for indication of the circuit breaker status ("no current condition"). The 7SV600 will operate correctly for both these conditions. The high security of the relay (against overfunction) is achieved with a fast current reset time and a 2-out-of-4 current measurement checks. The relay is suitable for use at all voltage levels and in all applications. The current transformers can either be of the closed iron core or linear type. The relay can be incorporated in conventional switchgear systems and modern substation control systems e.g. Siemens SICAM.
Functions

• Circuit-breaker failure protection (single- or three-pole with/without current)
  
• 2-out-of-4 current check
  
• Independently settable delay times for operation with and without current
  
• Single or two stage time delay of the busbar trip command
  
• Inter-trip facility (via teleprotection interface)
  
• End fault protection with intertrip
  
• "No current" condition control using the circuit-breaker auxiliary contacts
  
• Complete relay self monitoring
  
• Disturbance recording
  
• Fault and operating data (event records)
  

The 7SV512 is a numerical relay used for circuit breaker failure protection. This condition is when the circuit breaker fails to correctly open and clear the fault after single- or three-pole trip commands have been issued by the protection. It is then necessary to trip the relevant bus-bar zone (section) to ensure fault clearance. Generally, the monitoring of the current suffices as the criteria for the indication that the circuit breaker has successfully cleared the fault ("current condition"). However, under certain fault conditions, (e.g. overvoltage) little or no current may flow making the measurement of current unreliable for indication of the circuit breaker status ("no current condition"). The 7SV512 will operate correctly for both these conditions. The high security of the relay (against overfunction) is achieved with a unique microprocessor independent pole discrepancy protection is included. The relay is suitable for use at all voltage levels and in all applications. The current transformers can either be of the closed iron core or linear type. The relay can be incorporated in conventional switchgear systems and modern substation control systems e.g. Siemens SINAUT LSA.
Functions

• Circuit breaker failure protection (single- or three-pole with/without current)
  
• 2-out-of-4 current check
  
• Independently settable delay times for operation with or without current
  
• Single or two stage time delay of the busbar trip command
  
• Microprocessor independent trip release function (hardware interlock)
  
• Cross trip stage (1st stage of the 2 stage operation)
  
• Circuit breaker defective input facilitates a separate busbar trip time delay
  
• Inter-trip facility (via teleprotection interface)
  
• End fault protection with intertrip
  
• "No current" condition control using circuit breaker auxiliary contacts
  
• Pole discrepancy protection
  
• Complete relay self monitoring
  
• Disturbance recording
  
• Fault and operating data (event records)
  
• Selectable setting groups

Functions

• Single and/or three-pole auto-reclose
  
• Up to 10 auto-reclose shots
  
• Independently settable dead times and reclaim time
  
• Sequential fault recognition
  
• Check-synchronism with live line/dead bus, dead line/live bus, dead line/dead bus and
  
• Synchronism conditions (live line/live bus)
  
• Issue of close command taking the closing time of the circuit breaker into account
  
• Circuit breaker closing supervision, e.g. circuit breaker not ready facility
  
• Manual close function independently settable for autoreclose and check-synchronism
  
• Changeover on-line between 4 complete sets of parameters
  
• Event and fault recoding for the voltage inputs
  
• Event and status reports
  

The highly sensitive transient earth-fault relay 7SN60 determines the direction of transient and continuous earth faults in systems with isolated neutral, in systems with high-impedance resistive earthing and in compensated systems.