Sizing Data Tab (Cable Common Properties Dialog) - Intergraph Smart Electrical - Help - Hexagon

Intergraph Smart Electrical Help

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Provides information about the electrical load for a power cable The software uses this information as input values for cable sizing. When the cable has a connected load, the software copies the electrical parameters of the load to the cable. You can change the values of these parameters used for cable sizing if required. An asterisk beside a property name indicates required data for sizing.

Supply

Allows you to select the type of supply: alternating current (AC) or direct current (DC). If the cable is connected to a load for which you select the Consumer check box on the General tab of the appropriate load Common Properties dialog, the software copies the value from the load to this box. Note that the value of this property is automatically inherited from the load, converting equipment, or any other electrical equipment that this power cable is connected to.

The software calculates the cable cross-section size using different voltage drop formulas for AC and DC supplies.

Rated voltage

Allows you to select an appropriate operating voltage for a load associated with the cable. If the cable is connected to a load for which you select the Consumer check box, the software uses the value from the load.

When selecting Protection Setting in the Cable Sizing tab the system expects the user to enter the current rating of the protection device. The calculation algorithm is programmed so that when sizing the cable the system compares the load of the Full Load current (multiplied by the code factor if Use Code Factor is enabled) with the protection device setting and uses the larger amperage (Full Load Amp X Code Factor or Protection Setting) as the required ampacity.

Number of Phases

Select the number of phases in the power supply to the load: 1, 2, or 3. If the cable is connected to a load for which you select the Consumer check box, the software uses the value from the load. This property applies for an AC supply only. Note that the value of this property is automatically inherited from the load, converting equipment, or any other electrical equipment that this power cable is connected to.

  • The software calculates sizing for 1- and 3-phase supplies only, using a different voltage drop formula for each option.

  • When selecting Protection Setting in the Cable Sizing tab the system expects the user to enter the current rating of the protection device. The calculation algorithm is programmed so that when sizing the cable the system compares the load of the Full Load current (multiplied by the code factor if Use Code Factor is enabled) with the protection device setting and uses the larger amperage (Full Load Amp X Code Factor or Protection Setting) as the required ampacity.

Full load current (FLA

Enter the electrical current, in mA, A, or kA, that the cable must supply without causing damage to the insulation. The software uses the value of the full load current to calculate sizing involving the thermal calculation. Note that the value of this property is automatically inherited from the load, converting equipment, or any other electrical equipment that this power cable is connected to.

When selecting Protection Setting in the Cable Sizing tab the system expects the user to enter the current rating of the protection device. The calculation algorithm is programmed so that when sizing the cable the system compares the load of the Full Load current (multiplied by the code factor if Use Code Factor is enabled) with the protection device setting and uses the larger amperage (Full Load Amp X Code Factor or Protection Setting) as the required ampacity.

Starting current

(This is a required property for motors and some other loads) If a motor is connected to the cable, the software enters the value of the locked rotor current (LRC). For a motor, the starting current value can typically be 400 - 600% larger than the full load current and is therefore important when evaluating the current requirements used to perform sizing. Note that this option is available for all power cables whether they are connected to motors or not. When selecting Protection Setting in the Cable Sizing tab the system expects the user to enter the current rating of the protection device. The calculation algorithm is programmed so that when sizing the cable the system compares the load of the Full Load current (multiplied by the code factor if Use Code Factor is enabled) with the protection device setting and uses the larger amperage (Full Load Amp X Code Factor or Protection Setting) as the required ampacity.

Use code factor

You can specify whether to use an FLA multiplier factor for thermal ampacity calculations. The code factor affects the units of various quantities such as the cable size and the sizing calculation.  The standard options defined in the Data Dictionary Manager are:

Yes

The software multiplies the full load current by a factor set by the user in the Code Factor field. If yes is selected and no value entered in the Code Factor field then no calculation is made and the message is displayed: Enter a value in the Code field.

No

The software does not multiply the full load current.

The selection for this option also determines the available values of conductor size, frequency, and rated voltage.

Code factor

Allows you to type the value for the FLA multiplier.  The code factor value is used to multiply the FLA which is used to calculate the required thermal ampacity, if no value is entered then the software uses a factor of 1.  This field is only available when Use code factor is set to Yes.

Power factor at full load

Allows you to enter the power factor of the equipment that the cable feeds under normal full load running conditions. The power factor is the ratio of active power to apparent power and can have a value between 0 and 1. If the cable is connected to a load for which you select the Consumer check box, the software uses the value from the load. Note that if the power supply is DC, the power factor at full load and at starting is always 1 (one) and it cannot be changed. When selecting Protection Setting in the Cable Sizing tab the system expects the user to enter the current rating of the protection device. The calculation algorithm is programmed so that when sizing the cable the system compares the load of the Full Load current (multiplied by the code factor if Use Code Factor is enabled) with the protection device setting and uses the larger amperage (Full Load Amp X Code Factor or Protection Setting) as the required ampacity.

Power factor at starting

Allows you to enter the power factor of the equipment that the cable feeds under starting conditions. If the cable is connected to a motor for which you select the Consumer check box, the software uses the value from the motor. This property is not available for loads other than motors. Note that if the power supply is DC, the power factor at full load and at starting is always 1 (one) and it cannot be changed. When selecting Protection Setting in the Cable Sizing tab the system expects the user to enter the current rating of the protection device. The calculation algorithm is programmed so that when sizing the cable the system compares the load of the Full Load current (multiplied by the code factor if Use Code Factor is enabled) with the protection device setting and uses the larger amperage (Full Load Amp X Code Factor or Protection Setting) as the required ampacity.

Routing

Allows you to select an appropriate routing type for the current cable: InAir, UnderGround, or some other custom routing type that you define. The option that you select affects whether the software uses the ampacity value in air, in the ground, or custom basic ampacity when sizing a cable.

Auto-restart

Select this option to indicate whether a motor connected to the cable restarts automatically or manually after a power outage.  This property is not available for loads other than motors.

De-rating factors

The basic ampacity of the cable applies to standard conditions that the manufacturer specifies. Under actual operating conditions, such as a higher environmental temperature, or a location where several cables are routed close to one another, the ampacity changes  The de-rating and utilization factors take into account the operating conditions of the cable.

De-rating factor

Allows you to enter a value for the de-rating factor, which the software uses to calculate the cable de-rated ampacity under actual operating conditions. The software multiplies the basic ampacity by the de-rating factor to obtain the de-rated ampacity. A value of less than 1 means that the de-rated ampacity is lower than the basic ampacity, and this will result in a requirement for a larger size cable.

Utilization factor

Enter a value between 0 and 1 to represent an additional factor that de-rates the cable ampacity. If you do not need to use this property, set the value to 1. The software multiplies the basic ampacity by this factor to obtain the de-rated ampacity.

Ambient temp. factor

Enter a value between 0 and 2 to represent a temperature factor that affects the de-rated cable ampacity. For the software to apply this factor to the calculation, in the Options Manager, you must first set the value of the Apply Temperature Correction Factor to Cable Sizing property to Yes; setting the value of the property to No is the equivalent of using a value of 1 for the temperature factor.

If you change any of the de-rating factors for a sized cable, the software automatically selects the Sizing required check box on the General tab.

Voltage drop (%)

The cable needs to supply electrical current at a voltage that is no more than a few percentage points below the rated voltage.  The voltage drop is expressed as a percentage of the rated voltage.  The software compares the allowable and the recommended calculations of the voltage drop at running and starting conditions and uses the result to specify the smallest cable that meets the maximum voltage drop requirements.

Allowable at full load

Allows you to enter the maximum allowable voltage drop percentage when the connected load is running under normal full load conditions. The allowable voltage drop must have a value greater than zero. To ignore the voltage drop in the sizing calculation, type a value of 100.

When selecting Protection Setting in the Cable Sizing tab the system expects the user to enter the current rating of the protection device. The calculation algorithm is programmed so that when sizing the cable the system compares the load of the Full Load current (multiplied by the code factor if Use Code Factor is enabled) with the protection device setting and uses the larger amperage (Full Load Amp X Code Factor or Protection Setting) as the required ampacity.

Value in use

Displays the currently used calculated value of the percentage voltage drop of the cable when the load is running under normal operating conditions, using the actual length of the cable.

Allowable at starting

Allows you to enter the maximum allowable percentage voltage drop when starting the equipment. The allowable voltage drop must have a value greater than zero. To ignore the voltage drop in the sizing calculation, type a value of 100.

  • This is a required property for motors and some other load types.

  • When selecting Protection Setting in the Cable Sizing tab the system expects the user to enter the current rating of the protection device. The calculation algorithm is programmed so that when sizing the cable the system compares the load of the Full Load current (multiplied by the code factor if Use Code Factor is enabled) with the protection device setting and uses the larger amperage (Full Load Amp X Code Factor or Protection Setting) as the required ampacity.

Value in use

Displays the currently used calculated value of the voltage drop percentage of the cable when starting the motor, using the estimated or design length of the cable.

The software clears all the Recommended cable sizing results values and both Value in use entries in the Voltage drop % group box if you do one of the following. Also, the software turns on the Sizing required flag and you have to recalculate the cable sizing.

  • Replace the associated reference cable.

  • Turn a single power cable into a set of parallel cables by adding a parallel cable.

  • Turn a set of parallel cables into a single power cable by deleting parallel cables.

Short circuit

If you want to include short circuit calculations in the cable sizing, you enter values for the properties in this section.  The software uses this data along with the coefficients that are found in the Conductor Material Coefficients and Conductor Insulation Temperatures lookup tables to calculate the minimum required conductor cross-section area.  Suitable values must be available in these tables for the software to be able to perform the calculation.

Use short circuit cable sizing

Select to enable and activate the short circuit properties and algorithm when you want the cable sizing to include short circuit calculations.

Duration

Allows you to type the maximum time for which the cable is expected to withstand a fault short circuit current until a protection device interrupts the current flow in the circuit.

Fault current

Allows you to type the maximum short circuit fault current that can flow through the cable, and for which the cable needs to be sized.

Required area (cmils)

Displays the calculated minimum conductor cross-section area required for the cable to meet the short circuit criteria that you specify.

Protection setting

Allows you to specify cable sizing based on the rated current for a protection device such as a fuse or circuit breaker, rather than using the load current.

Include protection device

Select to specify the rated current of the protection device for use in sizing calculations.  Clear to use the load current value.

Protection settings

Allows you to type the rated current of the protection device for use in sizing the cable. When selecting Protection Setting in the Cable Sizing tab the system expects the user to enter the current rating of the protection device. The calculation algorithm is programmed so that when sizing the cable the system compares the load of the Full Load current (multiplied by the code factor if Use Code Factor is enabled) with the protection device setting and uses the larger amperage (Full Load Amp X Code Factor or Protection Setting) as the required ampacity.

Recommended cable sizing results

Displays the recommended sizing calculations based on the load data that you supply for the cable. All the information is read- only.

If the cable is connected to a load for which you select the Consumer check box, the software uses the electrical values of the load that are inherited by the cable to calculate the cross-section size of that cable.

Cross section

Displays the recommended cross section of the current-carrying conductors for the load requirement. You can select the ellipsis button to open the Cable Sizing Matrix and select another more suitable reference cable. See Cable Sizing Matrix Dialog.

  • The software does not size a cable for which it cannot find a reference cable with the specified cable specification that matches the value of the minimum conductor cross-section for parallel cables defined in Options Manager. You should either change the value in Options Manager or create a new reference cable with the appropriate cross-section in the Reference Data Explorer.

  • The software filters out from the Cable-Sizing Matrix all the reference cables whose insulation voltage rating is smaller than the rated voltage of the current cable. Also, the software does not allow a situation where the insulation voltage rating is smaller than the rated voltage of a given cable. This situation is prevented when:

    • Sizing a single cable or several cables in batch mode.

    • Refreshing load data in batch mode or by clicking the Refresh Data button on the Sizing Data tab.

    • Replacing the associated reference cable of one or more plant cables.

    • Manually modifying cable data on the Common Properties dialog box or the Properties window.

De-rated cable ampacity

Displays the recommended cable ampacity calculation under actual operating conditions. The software calculates the de-rated ampacity by multiplying the basic ampacity by the de-rating factor and the utilization factor.

Number of parallel cables

Indicates the recommended number of parallel cables required when no single reference cable meets the minimum cable sizing requirements.  The software creates parallel cables as a result of the sizing.  The cables are handled as an inseparable group, and any action that you perform on one of the cables causes all the cables in that group to follow that operation.

Voltage drop at full load

Displays the recommended voltage drop percentage of the cable when the connected load is running under normal full load conditions.

Voltage drop at starting

Displays the recommended voltage drop percentage of the cable when starting the equipment.

Maximum cable length

Indicates the maximum allowed cable length according to the recommended cross-section calculation.

The software clears all the Recommended cable sizing results values and both Value in use entries in the Voltage drop % group box if you do one of the following. Also, the software turns on the Sizing required flag and you have to recalculate the cable sizing.

  • Replace the associated reference cable.

  • Turn a single power cable into a set of parallel cables by adding a parallel cable.

  • Turn a set of parallel cables into a single power cable by deleting parallel cables.

Calculation Information

Displays messages related to verification of the sizing calculation such as missing data or indicating a cable-load association. Also displays a message if the current cable needs to be resized.

The software displays the message Not found when no suitable reference cable matches the sizing results under the following conditions: when no reference cable exists corresponding to the cable specification or arrangement, when there are missing values for ampacity, resistance, or reactance, or when the number of parallel cables exceeds the limit specified in Options Manager by the Maximum Number of Parallel Cables property.

System notes

Displays messages related to performed actions such as connecting a load, sizing, and so forth.

Command Buttons

Refresh Data

Updates any information derived from a load connected to the cable. This button is available when the load data changes since the previous time of sizing of the cable or when you perform cable sizing for the first time.

The software updates the values of the following properties for all item types if these properties have been defined:

  • Full load current (FLA)

  • Starting current

  • Rated voltage

  • Supply (AC/DC)

  • Number of passes

  • Power factor at full load

  • Power factor at starting

Calculate Sizing

Calculates the cable cross-section size using the input data and recommends the most suitable reference cable based on your selected cable specification and formation.

After selecting the Calculate Sizing button, the formulas and values used in the cable sizing calculations can be viewed on the Sizing Report tab.

Apply Sizing

Copies the data to the cable from the reference cable that the software recommends as a result of the cable sizing.

If you replace the associated reference cable of a terminated cable, the software does not allow you to resize this cable unless the new reference cable has the same conductor arrangement as the replaced reference cable.

Synchronize With Reference

Opens the Synchronize Plant and Reference Cable Data Dialog, which enables you to see if there are any differences between the values in the properties of the current plant cable and the values in the associated reference cable. You can then copy the reference data to the plant cable so that the plant and reference cable data is fully synchronized. Note that this command becomes available only when there is a difference between plant and reference data for the current item.