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1 Introduction
22
7ST6 Manual
E50417-G1176-C251-A3
Voltage Protection
(optional)
• Two-stage overvoltage and undervoltage detection
• Two overvoltage stages for the overhead contact line ( U>>, U> )
• Two undervoltage stages for the overhead contact line (U<<, U<)
Thermal Overload
Protection
• Determination of the overhead contact line temperature by creating a thermal profile
of the object to be protected
• Adjustable thermal alarm level
Circuit Breaker
Failure Protection
(optional)
• 2 independent time stages
• Tripping by 2 independent, adjustable monitoring time stages
• Start by trip command of every internal protection function
• External start possible
Defrosting Pro-
tection
• Differential protection for defrosting current with configurable characteristic
• Back-up protection with two-stage definite-time overcurrent protection
Inrush Restraint
(optional)
• Distinction between operating and fault condition by harmonics analysis
• Possibility of blocking selected protection functions
Automatic
Reclosure Function
(optional)
• Single or multiple reclosure (up to 8 reclosure attempts)
• With separate idle and operating times for the first 4 reclosure attempts
• Synchronism check before reclosing
Synchronism and
Voltage Check
(optional)
• Verification of the synchronous conditions before energisation;
• Fast measuring of voltage difference U
Diff
of the phase angle difference
ϕ
Diff
and
frequency difference f
Diff
• Alternatively, check of the de-energized state before energisation;
• Switching possible for asynchronous system conditions with prediction of the syn-
chronization time
• Settable minimum and maximum voltage
• Verification of the synchronous conditions or de-energized state also possible
before dispositive closing of the circuit breaker, with separate limit values;
Fault Locator
(optional)
• Start by tripping command or dropout of the pickup, even with high-current switch-
onto-fault protection
• Fault location output in
Ω
, kilometers or miles and % of line length;
Trip Load (optional)
• Detection and summation of interrupted currents
• Monitoring with It function (optional)
• Alarm output when limit is exceeded
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