CONFIDENTIAL TIBU3818-00

During normal operating conditions, the flywheel preheat cycle is not required unless the UPS system has been without power for more than 24 hours. In operating environments that are not climate controlled, this undue preheating process can result in excessive heating of the flywheel.

For exact operational instructions and procedures, refer to the following publications:

RENR2476, Systems Operations, Testing and Adjusting, "UPS250, UPS300, UPS500, UPS750, and UPS900 Uninterruptible Power Supply"

SEBU7464, Operation and Maintenance Manual, "UPS250, UPS300, UPS500, UPS600, UPS750, and UPS900 Uninterruptible Power Supply"

When the UPS is being commissioned or when the UPS has been de-energized for a period of 24 hours or greater, the UPS system requires that the flywheel assembly go through a preheating cycle. This preheating cycle is necessary to ensure that the rotor has achieved an acceptable operating temperature prior to motoring at rated speed. The typical preheating cycle is 42 minutes. In order to expedite the service process and to alleviate an unnecessary step, the preheating cycle time can be reduced or can possibly be by-passed under certain conditions.

In order to be eligible to reduce your preheating cycle time, the following criteria must be met:

1. The UPS must have Firmware 2.43 or higher.
2. The UPS system has not been de-energized within the last 72 hours.

1. Record the current ambient temperature where the UPS is located.
2. Record the length of time the ambient temperature (around the UPS system) has been stabilized at this temperature.
3. Record the Armature temperature.
4. Call 1-800-288-5081 to obtain a "Preheat" password and confirmation procedure. Be prepared to confirm that the criteria have been met and also be prepared to provide the above-recorded temperature values.

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