Liebert Series 610 user manual Tie Circuit Breaker or Logic Faults, Hardware Failures

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Operation Description

2.8Tie Circuit Breaker or Logic Faults

The Continuous Power-Tie system has been designed to anticipate circuit breaker and logic faults. Should a circuit breaker or logic fault occur, the Power-Tie system maintains the critical bus function under fault conditions

2.8.1What Happens If a Failure Occurs During a Power Transfer

During normal operation, the Power-Tie logic maintains system isolation. Upon power transfer initia- tion, the Power-Tie logic checks the circuit breaker (CB) positions. The Power-Tie logic inhibits the power transfer if the circuit breaker positions are incorrect.

For Continuous Tie, if all circuit breakers are in their correct positions, then all circuit breakers momentarily remain closed, tying both systems together. The power transfer sequence stops. The static bypass becomes the backup.

If the operator selects momentary Power-Tie, the isolation circuit breaker opens. If this circuit breaker fails to open, the system returns to its initial configuration, maintaining the critical bus.

2.8.2What Happens If a Logic Failure Occurs During Power Transfer

If a failure occurs before the power transfer, the Power-Tie logic inhibits the power transfer operation. If a failure during the power transfer, one of the following occurs:

•If the failure occurs before overlap period has timed out, the Power-Tie logic returns the system to its initial configuration.

•If failure occurs after overlap period has expired (e.g., the isolating breaker has already been com- manded to trip), the Power-Tie logic completes the transfer.

•If the power transfer does not complete (e.g., the isolating breaker fails to trip within an accept- able time period), the Power-Tie logic returns the system to its initial configuration.

•If the failure occurs after the transfer has occurred, the static bypass becomes the backup.

2.8.3Hardware Failures

Improper operation of the Power-Tie are caused primarily by tie circuit breaker failures. The Power-Tie logic monitors the “Close” and “Open” sent to the circuit breakers. If the breaker command is not completed by the breaker within an acceptable time period, the Power-Tie logic takes corrective action. The Power-Tie implements corrective action based on the operation being performed and the current system configuration.

The Power-Tie logic takes protective action if a fault occurs on a UPS system during a load transfer or while the UPS systems are in continuous parallel operation. The Power-Tie logic takes action based on the current system configuration and the active operation to minimize the affects of the fault.

The Power-Tie controls add additional protection to the individual UPS systems. And, the protective controls of the individual UPS become an integral part of the overall fault protection scheme used by the Power-Tie controls.

2.9Recommendations - Tie Circuit Breaker Selection

Consider using non-automatic circuit breakers for continuous Power-Tie applications. The circuit breaker function should not be the primary fault limiting function. Using non-automatic circuit breakers eliminates a primary circuit breaker failure mode, the trip unit components within the cir- cuit breaker.

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Contents Continuous POWER-TIE Configuration Page Table of Contents Initial System Start-Up 4.2 Basic Operation Operating InstructionsInter-System Isolation and Reliability FunctionSystem Flexibility Basic Dual-Bus Power-Tie one-line diagram Power-Tie systems fault isolation issues Power-Tie systems control interface diagram Operational Description Control System FeaturesMomentary Tie Transfer Controls Momentary Tie OperationIntersystem Synchronizing Continuous Tie Intersystem Sync and Power SharingTie System Components Continuous Tie/Transfer/Parallel ControlModes of Operation Power-Tie system one-line diagram Synchronizing the UPS Systems Continuous Power-TieChecking for Phase, Voltage, and Capacity Selecting a Line Sync SourceControl panel layout Load Transfers Between UPS Systems Separating Tied SystemsDesign Criteria Combined Loads on One System from Continuous Tie OperationCombined Loads on One System to Continuous Tie Operation Line Sync Signal Power-Tie system fault isolation issues Power-Tie systems fault tolerance Tie Operation Improper User OperationTransfer Operation Hardware Failures Tie Circuit Breaker or Logic FaultsWhat Happens If a Failure Occurs During a Power Transfer Recommendations Tie Circuit Breaker SelectionMimic Panel Load Transfer Controls Transfer Function Available OK to Transfer Load 2 to System Transfer Control DisabledTransfer Function Available Transfer Function Available OK to Transfer Load 1 to SystemControl Inhibits Continuous Tie ControlManual Controls Basic Operation Normal Transfer Operation ConfigurationsMaintenance Procedures Isolating Each UPS System Initial System Start-UpTransfer of Load Between Two Systems Maintenance Procedures Tie Control Logic Components Maintenance Procedures Maintaining Power-Tie ComponentsCircuit Breaker Failure Trouble RecoveryAbnormal Operations Improper TransferTying the UPS Systems Continuous Parallel Operations Normal Operating ConfigurationContinuous Tie-Systems Abnormal Operations Isolation for Maintenance Power-Tie system one-line diagram Operation Scenarios/Transfer Procedures See 4.2.5 Transfer of Load Between Two Systems See 4.2.4 Isolating a UPS System for MaintenanceCombined Loads Operation Parallel Operations See 4.2.11 Tying the UPS Systems ContinuousUPS System See 4.2.3 Maintenance Procedures Isolating EachOne system in bypass to Continuous Tie operation Option Operating Instructions Page Locations Technical Support/ServiceCompany Behind the Products
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