Bus Data

Uniquely identifies the equipment item. The program automatically assigns a name, but you can change it, if needed. The name can be up to 16 characters long.

For buses, the program automatically assigns the names BUS-1, BUS-2, BUS-3, and so on.

Base kV for the bus. Note that the bus must have a kV entered before equipment can be connected to the bus. Anything less than 1 kV is considered low voltage, anything 1 kV or more is high voltage. MCCs and panel schedules can only be connected to low voltage buses.

For DC buses, see also DC Bus - Base Voltage Specifications.

Type of equipment inside which the bus exists. The bus type definition is important for auto-design and arc flash hazard calculations. In arc flash hazard calculations, the parameters affected by type are the gap between conductors and the distance exponent. The various types are:

• Switchgear: This can be low voltage or high voltage switchgear.
• Open Air: The bus has no enclosures.
• Conductor: Wire ways, bus ways, and so on.
• MCC: Motor Control Center.
• Panel: Small and lighting panels.
• Panelboard: Low voltage power panelboards.
• Switchboard: This can be a low voltage or high voltage switchboard.
• NEMA E2 Contactor: NEMA E2 motor starter enclosures. The power voltage is at medium voltage. For low voltage control circuits this type can be used.
• Int Switch: Interrupting or disconnect or safety switch.
• VFD: Variable frequency drive or some type of motor drive.
• UPS: Uninterruptible power supply.
• ATS: Auto or manual transfer switch.
• Transformer Terminal: Enclosure transformer terminals/bushings.
• Vault: Underground space such as manhole for cable connections, transformers, and so on.
• Padmount Equipment: Padmount switches, padmount transformers cabinets, and so on.
• Control Panel: Enclosure for control circuits.
• Junction Box – Large: Large or deep junction box.
• Junction Box – Small: Small or shallow junction box.
• Network Protector: Spot or grid network protectors used in network distribution systems.
• Other: Any other type not specified.

Short circuit rating of bus bracing in kA. The testing standard unit is specified on the right as follows:

• A high voltage bus can have asymmetrical kA or peak kA (crest) units.
• A low voltage bus has symmetrical kA units.

Area numbers are used to uniquely define different areas of the electrical system. These areas can then be used for creating specific text reports from analysis operations that represent subsets of the system. For example, typical paper plant areas may be the power house (Area 1), caustic plant (Area 2), pulp mill (Area 3), and paper machine (Area 4). Area numbers are positive integers between 1 and 999.

A zone number is simply a sub-area. This enables even more specific reporting. You may want to define the pulp mill as Area 3 and the digester electrical equipment as Zone 2. Specific reports can then be generated for this combination without including the entire pulp mill or the other digesters.

The number shown is the diversity factor of the downstream bus with an equipment type of Switchgear, Switchboard, or Panelboard. If another equipment type is selected, the diversity factor is set to 1. Diversity factor is used in calculating the connected, demand, code and design kVA. The diversity factor is the ratio of the sum of the maximum demands of the individual loads to the maximum demand of the entire system, include all of those loads. Click Calculate Downstream Load to update the diversity factor.

Specify how you would like arc flash results determined for this bus.

Calculated: When calculated is selected, Trip times for this bus and Working Distances sections become available.

Excluded: Select to exclude the bus from arc-flash reports. Some examples of when excluded might be selected are buses that are on utility side (not worked on by company employees) but still modeled on the one-line and buses where energized work is not likely (splices).

Forced To: When selected an additional cell will appear where you can enter the incident energy for this bus. The arc flash value incident energy entered for this bus is shown on the one-line and in the Arc Flash Hazard Report. This is typically used for buses where the NFPA-70E has stated a particular PPE level can be assumed if certain conditions exist. Particularly, 208 volt equipment fed by 125 KVA or smaller transformers.

This specifies whether to display results on the line side or the load side of the Main protective device of the bus equipment. If the arc flash hazards output for this bus needs to be different from the global option, use this field. The choices are:

• <<Use Global Option>>: Use the option specified in Short Circuit Options.
• Including Main: Always display the arc flash hazard results on the load side of the Main protective device for this bus equipment regardless of what options are selected in the Short Circuit Options.
• Excluding Main: Always display the arc flash hazard results on the line side of the Main protective device for this bus equipment regardless of what options are selected in the Short Circuit Options.
• Both (Incl & Excl Main): Always display the arc flash hazard results on both the line side and the load side of the Main protective device for this bus equipment regardless of what options are selected in the Short Circuit Options.

Select method for determining trip times for this bus by choosing on the following:

• Pre-defined Fixed Times: Obtains arc clearing time for the bus from the library default values. This is not the same as the trip times calculated form the TCC curves of the upstream trip device. The values stored in the library are simply predefined approximate trip times. This method is not recommended. This option is a legacy method.
• User-defined Times: With this option you can specify the protective device clearing time for each bus. The details of arcing time for the bus can be specified in the fields – Device ID, Relay Function and Time (s). If no time is specified then the arc flash results do not appear.
• TCC Times (Automatically Calculated): Arc flash incident energy are calculated based on time characteristic current curves specified in each protective device data dialog box.
• User-Defined and TCC Times: Provides results for both user-defined times and TCC times as described above.
• User-Defined One-line Device: With this option, you can specify which device you want to use for the TCC time, and the program will obtain the trip time automatically. You can select a device type (relay fuse, or low voltage breaker) and device ID. If you select a relay, you also select the relay function.

Specifies the working distances shown on the one-line and in the arc flash hazard report.

• Default from Options: When selected, workings distances used are from the Default Working Distances spreadsheet in the Arc Flash Hazard Options.
• User Specified: Selecting this option allows you to enter the working distance for this bus only.

The units displayed are based on the units selected in Arc Flash Hazard Options on the System tab.

• For inches, the range is 1-1000.
• For meters, the range is 0.1 to 1000.

This is the orientation of the bus with respect to a worker that may be exposed to arc flash. This is not related to the vertical and horizontal buses in MCC and Switchgear. Arc travels away from the source and extends from the tip of the conductors. Based on the orientation of the conductors, the incident energy can vary. This choice affects the calculations factor (C_f) used in the arc flash hazard equations.

See Orientation for more information.

Select the power type for the equipment. The options are:

• NPS: Normal Power Supply. For example, a power supply that has no backup.
• CPS: Critical Power Supply. For example, a power supply that includes an uninterrupted power supply backup.
• EPS: Emergency Power Supply. For example, a power supply that uses a generator for backup.

The panel type for the bus. Select from:

• (Other)
• Tool
• Facility
• Tool/Facility

For the bus to be used as a tool point of connection, the type must be Tool or Tool/Facility.