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.

The phase of the item. Currently, this is for reference only.

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.

For the bus types ATS, switchgear, switchboard, panelboard, panel and MCC, you can fault buses and store the short circuit current and arc flash results in the database. These results can be displayed in schedules for switchgear, switchboard, panelboard, panels and MCCs. The stored results can also be viewed in the database browser and report. See Storing Short Circuit and Arc Flash Results for more information.

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.

You can specify how you would like arc flash results determined for this bus using AF for this Bus.

Calculated: When the bus is faulted, EasyPower the performs arc flash hazard analysis using the calculation method specified in Short Circuit Options. EasyPower uses other settings on this tab as part of the calculations.

Excluded: Select to exclude the bus from arc flash reports. An example of when you might select this option is for a bus that is required to model the electrical parameters of the system but does not actually represent a piece of electrical equipment. Other applications include nodes and tap-offs (junctions), where energized work is not required.

Forced To: When you select this option, you can enter the incident energy and arc flash boundary for this bus. The incident energy and arc flash boundary values are shown on the one-line and in reports and work permits. This can be used for instances where you need to apply a calculation that is outside the scope of the industry standard calculations.

You can specify 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.

You can select the method for determining trip times for this bus by choosing from 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 is a legacy method and is not recommended.
• 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). When this option is selected, a time must be specified.
• TCC Times (Automatically Calculated): Arc flash incident energy are calculated based on time characteristic current curves specified in each protective device data dialog box. The trip clearing time of the equipment where the device is a relay controlled breaker is the sum of the breaker mechanism opening time (for example, 3, 5, or 8 cycle), the relay trip time, and any time entered into the Relay Data, System, and Aux Time data fields.
• 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.

Note: When a user-defined time is specified and the calculation method is set to use the integrated method, only the upstream device setting is used. The time is considered as the maximum length of the simulation. See The Integrated Method for more information.

You can specify the working distances shown on the one-line and in reports and work permits.

• Default from Options: When selected, the program uses the workings distances from the Default Working Distances spreadsheet in the Arc Flash Hazard Options.
• User Specified: Selecting this option enables you to enter the working distance for this item.

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.

You can specify the electrode gap shown on the one-line and in reports and work permits.

• Default from Library: When selected, the program uses the electrode gap from the device library.
• User Specified: Selecting this option enables you to enter the electrode gap for this item. The range is between 0.1 and 25,000 mm.

You can specify the electrode configuration shown on the one-line and in reports and work permits.

• Default from Library: When selected, the program uses the electrode configuration from the device library.
• User Specified: Selecting this option enables you to select the electrode configuration for this item. The options available are based on the orientation of the electrodes, whether they are inside an enclosure, and in one instance, whether they terminate into a barrier.

Electrodes in Enclosures:

• VCB: Vertical electrodes inside an enclosure.
• VCBB: Vertical electrodes terminating in an insulating barrier inside an enclosure.
• HCB: Horizontal electrodes inside an enclosure.

Electrodes in Open Air:

• VOA: Vertical electrodes in open air.
• HOA: Horizontal electrodes in open air.

You can select more than one configuration to represent the multiple types of conditions that can occur for the equipment. EasyPower evaluates each configuration and then provides values for the highest incident energy based on the existing electrode configurations. Annex C in the IEEE 1584-2018 standard describes examples where you might use more than one electrode configuration.

Tip: To change the electrode configuration for multiple items on the one-line, select the items in the Database Edit focus and then on the Home tab, click Change > AF Bus Electrode Configuration.

Electrode configurations are only applicable to the IEEE 1584-2018 standard. For more information, see Electrode Configuration.

You can specify the enclosure size shown on the one-line and in reports and work permits.

• Default from Library: When selected, the program uses the enclosure size from the device library. The library provides typical values based on the equipment type and voltage.
• User Specified: Selecting this option enables you to enter the enclosure size for the item. This enables you to get more accurate calculation results, assuming the correct dimensions are entered.

The units displayed are based on the units selected in Arc Flash Hazard Options on the System tab. For inches, the range is .01-1000. For millimeters, the range is 0.1 to 25,000.

The enclosure dimensions affect arc flash.

• Arc flash is greatest for a 20 in. x 20 in. x 20 in. enclosure.
• Arc flash decreases as the height or width dimensions increase.
• In low voltage equipment with a height and width of less than 20 inches, arc flash decreases if the depth dimension is less than or equal to 8 inches.

Enter the number of labels you want to print for arc flash hazard analysis. If you enter "0," no labels will print.