Liebert Series 610 Initial System Start-Up, Basic Operation, Momentary Tie Load Transfers

Operating Instructions

4.0OPERATING INSTRUCTIONS

Refer to Figure 5.

4.1Initial System Start-Up

All load circuit breakers and tie circuit breakers are initially open.

1.Press the CLOSE LOAD 1 button located on the panel behind the Control door. The Load 1 breaker should close when the button is pressed.

2.Press the CLOSE LOAD 2 button located behind the Control door. The Load 2 breaker should close when the button is pushed.

NOTE

The operation can be performed with the UPS on bypass or inverter output. The Power-Tie logic confirms that the Tie breaker is open to prevent inadvertently putting the systems in parallel.

3.Once one or both UPS systems are on-line, a transfer of either critical load between systems or a continuous tie operation can be performed subject to conditions outlined in 1.0 - System Description and 2.0 - Operation Description and the following sections.

4.2Basic Operation

4.2.1Momentary Tie - Load Transfers

A momentary tie operation is used to transfer a critical load from a UPS system, which requires isola- tion for maintenance, to another UPS system without placing the critical load on utility bypass.

The isolated UPS system can be serviced while the critical load remains protected by a fully func- tional UPS system. Once service is complete, perform another Momentary tie operation to return the critical load to its normal UPS system. This can be done without placing the critical load on utility bypass.

4.2.2Normal Transfer Operation Configurations

Transfers of a critical load between systems can be performed from several initial system configura- tions. The guiding criteria for permitting transfers is that the critical load must remain on UPS inverter output.

Transfers to a UPS system operating on its bypass source cannot be initiated due to logic lockouts. However, a critical load initially on a UPS system’s bypass source can be transferred to the other UPS system operating on inverter output.

In addition to checking system configurations, the Power-Tie logic uses three independent criteria for verifying synchronization. The Power-Tie logic verifies system voltages are within proper limits. And the Power-Tie logic verifies the UPS system which will accept the additional load has sufficient UPS capacity.

The logic intelligently determines which system to synchronize with, which UPS system capacity to check, and which load(s) to check, based on which system the operator selects to transfer load. The Power-Tie logic “knows” the present system configuration.

The Power-Tie logic automatically returns both UPS systems to independent operation by resynchro- nizing them to their own bypass source and separating all control loops between the systems when the transfer is complete.

4.2.3Maintenance Procedures - Isolating Each UPS System

Power-Tie system capabilities permit each UPS system to be completely isolated for service while its load continues to be powered and protected by the other UPS system. In addition, since all controls of each system are electrically isolated from the other system, any operation or fault on the system being serviced does not affect the system supplying the combined loads.

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