I. Introduction
As building and plant sizes grow, particularly when there are high currents involved and many circuits to feed along the length and breadth of a facility, it often becomes cost effective to distribute plant power using plug-in bus systems as the primary conductors rather than conduit and wire. Plug-In type allows the bus to be used as a distribution system with disconnect devices installed, or “plugged-in” throughout the runs. These devices usually include circuit protection by way of fusing or circuit breakers, but not always. These disconnects may feed another distribution system like a panel board or they may feed a single machine.
Feeder bus systems are typically very high current systems where running wire would demand that the conduits be very large and run in multiples in order to provide the necessary current. Feeder duct allows very high current runs in single enclose busways but these are not designed to provide disconnecting means along the way.
II. Components
Part and assemblies to be reconditioned under Sections 2010/2020 standards LOW VOLTAGE BUS DUCT include but are not limited to:
- Bus enclosure
- Bus splice system
- Bus conductor
- Cover plates
- Insulating materials
- Hanger assemblies
- Gasket material
III. Standards
The PEARL Sections 2010 and 2020 LOW VOLTAGE BUS DUCT PLUG-IN/FEEDER TYPE Standards begins with the definition of the term “Reconditioning” as “the process of returning electrical equipment to safe and reliable operating condition based upon the design of the original manufacturer at the time of manufacturing.” This is followed by reference tables used to calculate test results and tolerances and the necessary test equipment required by the LOW VOLTAGE BUS DUCT PLUG-IN/FEEDER TYPE standard. The LOW VOLTAGE BUS DUCT PLUG-IN/FEEDER TYPE standard continues with a “Recondition Evaluation,” which is a detailed inspection of all parts of the disconnect switch, including but not limited to the components listed above.
IV. Testing and Inspection
Section I for PEARL Section 2010 and 2020 LOW VOLTAGE BUS DUCT PLUG-IN/FEEDER TYPE, begins with reference table identification and identification of the test equipment necessary to complete the standard, including one or more:
1. Insulation Resistance Test Set (Megohmeter) 1000 Vdc minimum
Also, one of the following pieces of test equipment is required to perform the overpotential testing requirements of this reconditioning standard if it is required by the customer:
1. AC Overpotential Test Set
2. DC Overpotential Test Set
Section II Recondition Evaluation-Inspection and Testing identifies each component and assembly part that must be inspected to determine the components viability and the scope of reconditioning required to bring the component back to original operating condition. Results and notes from the pre-reconditioning inspection and test are recorded in the PEARL Reconditioning Evaluation and Test forms that accompany each respective standard.
V. Reconditioning
Section III Reconditioning Procedures describes how to recondition each component and assembly, beginning with the disassembly of the motor control unit down to its major subassemblies. Reconditioning for LOW VOLTAGE MAGNETIC STARTERS OPEN includes:
- Disassembly
- Cleaning
- Degreasing
- Deburring
- Plating
- Painting
- Lubricating
- Adjusting
Assembly of the reconditioned components and subassemblies is followed by final inspection and testing. As with all testing, inspection, and reconditioning operations, final inspection and test results are recorded onto the Evaluation and Test forms included with the standard. If a PEARL certified technician follows the reconditioning standard, the LOW VOLTAGE BUS DUCT PLUG-IN/FEEDER TYPE assembly is eligible for a Blue PEARL Reconditioned Quality Seal.
Link to the full Standard Number 2010
Low Voltage Plug-In Type Bus Duct
Link to the full Standard Number 2020
Low Voltage Feeder Type Bus Duct
Link to view and/or download PEARL's 137 reconditioning standards for electrical equipment.
