Liebert Series 610 - Manual (Page 22)

Operation Description
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2.7 Improper User Operation
See Figures 4 and 5. The Power-Tie Operator controls and logic are designed so that improper opera-
tor use does not directly cause a loss of critical bus functions. Additional security functions, such as
removable key switches, are available as system options.
Transfer Operation
Transfer functions require two push-button operations. Pushing any single button at random, does
not put the system at risk. The Power-Tie system has redundant status sensors and monitors them
for proper operation.
The operator should use good judgement when operating the Tie Control. The Tie Control cannot pre-
vent an operator from tying to a source that subsequently goes bad.
For example, assume one UPS has gone to bypass. You want to bring the bypass feeder onto the sec-
ond system. The second system must momentarily tie to the first system’s bypass source. If a bypass
fault occurs in the first system during the tie operation, both load feeders could fault. To prevent this
type of fault, put the first system’s bypass source on a standby engine generator.
Tie Operation
The tie process only requires selection of the desired Primary Bypass Source (which may be left in a
default desired position) and the sequential pushing of two buttons. The Power-Tie logic takes care of
synchronizing to the select Primary Bypass Source, checking that the systems are in an acceptable
configuration, verifying that electrical parameters are within tolerance, and verifying sufficient com-
bined systems capacity.
The sequential operation serves both to eliminate accidental operation and allows the operator an
opportunity to cancel an undesired action. Before a transfer or tie operation can be performed the
Power-Tie control turns on an OK indicator.
The OK indicator clearly describes the action which will occur.
If the action indicated is not the desired action, the operator simply presses the button he used to ini-
tiate the original operation and the operation is canceled. Directions on how to use the “Push Again to
Cancel” feature are posted on the Power-Tie control panel, next to each applicable push button.