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POWER AVAILABILITY
CONTINUOUS POWER-TIE CONFIGURATION
USER MANUAL
Series 610
Multi-Module UPS
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TABLE OF CONTENTS 1.0 SYSTEM DESCRIPTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1 1.1 Function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 1.2 System Flexibility. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 1.3 Inter-System Isolation and Reliability . . . . . . . . .
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4.0 OPERATING INSTRUCTIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .25 4.1 Initial System Start-Up . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 4.2 Basic Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 4.2.1 Momentary Tie - Load Transfers. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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System Description 1.0 SYSTEM DESCRIPTION 1.1 Function The Liebert Continuous Power-Tie system provides the capability to momentarily or continuously parallel the output buses of two otherwise independent UPS Systems (See Figure 1). It also provides manually initiated, uninterrupted transfers of a critical load bus between the two UPS Systems. This topology permits one UPS and its associated distribution system to be shut down for mainte- nance while the load continues to be supplied by anoth
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System Description Figure 1 Basic Dual-Bus Power-Tie one-line diagram 2
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System Description Figure 2 Power-Tie systems - fault isolation issues 3
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System Description Figure 3 Power-Tie systems - control interface diagram 4
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System Description 1.4 Control System Features A key control feature necessary for successful momentary or continuous tie operation of two UPSs is the dynamic load current sharing function. A key design requirement for maximizing multiple system reliability and inverter availability in tied configurations is assuring maximum system independence under the normal, separated operating conditions. Liebert has incorporated a number of unique solutions in your Power-Tie System to accomplish these
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System Description 1.5.2 Momentary Tie Operation See Figure 3. Momentary Tie operation provides manually initiated, uninterrupted transfers of a critical load bus between two otherwise independent multi-module UPS systems. This topology permits individual UPS shutdown for maintenance while its load continues to be supplied by another UPS without the necessity of transferring the load to bypass during shutdown or restart of the UPS being maintained. A major goal in the design of Momentary Tie
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System Description The Tie Control Unit also contains interlock and monitoring circuitry necessary to assure successful transfers of load between UPS systems. These consist of the following: 1. Sync Verification circuitry, similar to the circuitry employed in each UPS, provides the sync check function in two independent modes: a. Phase Difference detection for ±3 degrees. Phase Difference inhibits a transfer if limits are exceeded. b. Voltage Difference detection for ±3%. Voltage Differential
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System Description Synchronizing activity takes place automatically once the preferred source is chosen and a manually initiated SYNCHRONIZE SYSTEMS signal is given. Visual indicators show that the systems are synchronizing and when the systems are ready for the manually initiated, automatically controlled paralleling sequence. Continuous Tie/Transfer/Parallel Control The transfer load and tie controls operate the tie breakers between systems in a sequential manner to allow paralleling and
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System Description 1.5.5 Modes of Operation See Figure 4. The Power-Tie Uninterruptible Power System is designed to operate in the following modes: 1. Normal - Each load bus is fed from its respective UPS and the tie breaker is open. Each inverter is synchronized to its respective bypass source. Each load is supplied by its inverter(s), with its bypass available as an alternate source. 2. Momentary Tie - The load bus and the two UPSs are momentarily paralleled through the tie breaker. Both UP
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System Description Figure 4 Power-Tie system one-line diagram 10
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Operation Description 2.0 OPERATION DESCRIPTION There are two types of operations which can be performed with the Liebert Continuous Power-Tie System. Create a continuous tie between the critical buses of two UPS systems Transfer of a critical load between two UPS systems 2.1 Continuous Power-Tie The following sequence of operations describe the actions to take to continuously tie two UPS systems together. See Figure 5. Selecting a Line Sync Source From the Continuous Power-Tie Control Pan
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Operation Description Figure 5 Control panel layout 12
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Operation Description 2.2 Separating Tied Systems The following sequence of operations describes the actions taken to separate two tied UPS systems. Synchronize Systems From the CONTINUOUS TIE CONTROL section, press the SYNCHRONIZE SYSTEMS button. The buttons light turns off to provide a visual indication of the operators intention to separate the sys- tems. The SYNCHRONIZE SYSTEMS button toggles between indicating the intention to parallel or separate the two UPS systems. Verifying Capacity
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Operation Description 2.4 Combined Loads on One System from Continuous Tie Operation To combine two loads onto one system, perform a LOAD TRANSFER BETWEEN UPS SYSTEMS (2.3 - Load Transfers Between UPS Systems). The operator selects the system he wants to main- tain both loads using the TRANSFER LOAD TO buttons. The operator can then proceed with the rest of the procedures in 2.3 - Load Transfers Between UPS Systems. 2.5 Combined Loads on One System to Continuous Tie Operation To create a conti
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Operation Description Line Sync Signal The Line Sync signal is sent between UPS systems when they are in parallel. Isolation amplifiers iso- late the Line Sync signal levels between the two systems. The Line Sync signal synchronizes the UPS systems to the Primary Bypass line. By maintaining sync with the Primary Bypass, uninterrupted transfers to the Primary Bypass can be made, if a fault occurs while the systems are in parallel. All status signals sent between the UPS system and the Tie Contr
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Operation Description Figure 6 Power-Tie system - fault isolation issues 16
