TURBOCHARGER GP 2627102 - Caterpillar

UMBC Component and Operation Overview
The UMBC is a logic circuit board. The UMBC controls the maintenance bypass breaker (MBP) and the maintenance isolation switch (MIS). The MBP and the MIS are motorized circuit breakers in a UPS maintenance bypass circuit. If appropriate conditions are met, the UMBC performs transfers to and from maintenance bypass with a closed transition. If installed correctly, the UMBC will also prohibit closed transitions if a "dead bus" is detected. The MBP connects the incoming utility power to the load while bypassing the UPS. The load is not protected when the system is in "Bypass". The load will be affected by a disruption of the incoming power. The UMBC will prevent back feeding to the utility. Back feeding can damage utility equipment and injure utility workers and provides an overlap transfer between the MBP and MIS. The following figure shows the UMBC cabinet.
Illustration 1 g03379668
Universal maintenance bypass cabinetWhen correctly installed and operated, the UMBC can prevent damage to equipment and injury or death to personnel due to problems from the following:
Over voltage that is +10% of nominal (480/400 VAC)
Under voltage that is -10% of nominal (480/400 VAC)
Phase rotation
Single phase conditions
Over and under frequency + or -10% of nominal (50/60 Hz)
Transfer to or from maintenance bypassThe following diagram shows the operational circuitry of the UMBC. Also shown is the MBP breaker and that MIS breaker that is controlled by the UMBC.
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Typical example of a UMBC installationMaintenance Bypass Breaker (MBP) Operation Overview
The MBP is a motor operated, stored energy breaker. The MBP breaker is controlled by the UMBC to transfer the system to and from maintenance bypass. The MBP works as a transfer pair with the MIS.Maintenance Isolation Switch (MIS) Operation Overview
The maintenance isolation switch is one of the two breakers that make up the optional maintenance bypass breaker pair. The switch is located between the common output of the UPS and the load bus.Become familiar with the components, the designations, system locations, and operation. The system records and displays messages that refer to the components and the operating states.