HUB AS-COUPLING 2634996 - Caterpillar

CONFIDENTIAL TIBU4060-00
TECHNICAL INFORMATION BULLETIN February 11, 2004
Uninterruptible Power Supply UPS 300 (CNJ, CPZ)
UPS 301 (CSY)
UPS 600 (CTX)
UPS 900 (CRY)
UPS 250 (APZ, CNM, BEE)
UPS 500 (CSE)
UPS 750 (CPM)
Component Codes: 4480SUBJECT: Troubleshooting and Repair of Vacuum Leaks.
PROBLEM: Problems have been reported by UPS commissioning technicians. UPS units in storage for six months or greater have had problems achieving a proper vacuum on the flywheel. Technicians report that the black polymer elbow (suction side) of the vacuum pump (Cat p/n 180-6246) is causing the leak. Replacement of the elbow has achieved acceptable results. However, Failure Analysis Reports do not concur with these results. Failure Analysis Reports do not show any structural defects in the elbow which would cause the vacuum leak.
: Personal injury or death can result from high voltage.
When the flywheel is spinning, the following components are energized: the bus, the armature leads, and the flywheel armature fuses.
High voltage and current are present when the Uninterruptible Power Supply (UPS) equipment is in operation.
Improper test equipment can cause a high voltage shock hazard to the user.
Make sure that testing equipment is designed for and correctly operated during high voltage and high current testing.
SOLUTION: After review of the Failure Analysis Reports, the o-ring seal of the polymer elbow (suction side of the vacuum pump) is the suspected vacuum leak. The o-ring seal is concluded to have dried out due to the extended storage period of the UPS. Re-lubricate the o-ring seal on both sides of the elbow using the approved High Vacuum Grease (Cat p/n 6V-2055).
As a precaution, when removing foam shipping materials surrounding the vacuum pump assembly, do not exert any undue force on vacuum hoses. Hoses could be entangled within the shipping material. This could result in loss of a proper seal at the o-ring.
In order to provide further assistance in troubleshooting a vacuum leak, the following information is provided.
When the system is first energized, a vacuum reading of 9999T could be displayed. This is normal. This value indicates the interior flywheel atmosphere equals the exterior atmosphere. This value will change as the vacuum inside the flywheel changes. The next probable value displayed is 2400T. This indicates that the flywheel is achieving a vacuum draw, but the vacuum is out of the range of the sensing device.
A vacuum reading on the flywheel of 30mTorr or less is proper. A flywheel, which has been commissioned and operated for a week can have a vacuum reading of 18 to 23mTorr.
When performing the "flywheel preheating process", an initial vacuum reading of 50mTorr or greater is expected. The display an alarm (yellow light) when the vacuum reaches 60mTorr. The alarm status will change to normal when the vacuum drops to 57.3mTorr. The UPS vacuum reading will cycle up and down during the preheating. This is normal. (Note: the Preheat processing time cycle is 42 minutes and must be complete the entire period. Refer to TIBU3818-00). If the vacuum reading is above 30mTorr after completion of the Preheat cycle time, check the armature temperature. If the