AUWiring

Motor overload setting worksheet calculator

Estimate a motor overload setting worksheet value for Australian motor records from entered full-load current, service factor, setting percent and device range assumptions.

  • Calculator
  • Motors
  • Australia
Use the motor schedule, starter record or asset label so the current basis can be checked later.
A
Enter the current basis from nameplate, schedule, manufacturer data or a documented estimate.
x
Enter the service-factor basis from the motor or project record.
%
Enter the overload setting percent used for this worksheet row.
A
Optional. Enter a project or device setting value for comparison.
A
Optional. Enter the lower end of the device adjustment range when documented.
A
Optional. Enter the upper end of the device adjustment range when documented.
Ipercent = IFLC x setting_% / 100; Iservice_limit = IFLC x service_factor; Iworksheet = min(Ipercent, IFLC x service_factor); Irange_low_margin = Iworksheet - Idevice_min; Irange_high_margin = Idevice_max - Iworksheet; Ireview_margin = Ireview - Iworksheet
  • Full-load current, service factor and setting percent are entered by the user.
  • Device range values are optional but must be entered as a pair.
  • Review setting is optional and should be used only when a documented comparison value exists.
  • The worksheet does not choose a device or reproduce manufacturer setting tables.
Formula variables
VariableMeaningUnitUse
IFLCFull-load currentAMotor current entered from nameplate, schedule, manufacturer data or a documented estimate.
setting_%Setting percent%Entered percentage basis for the worksheet row.
service_factorService factorratioEntered service-factor basis used as an upper worksheet limit.
IpercentPercent settingAFull-load current multiplied by setting percent.
Iservice_limitService-factor limitAFull-load current multiplied by service factor.
IworksheetWorksheet overload settingALower value of percent setting and service-factor limit.
Idevice_minDevice range minimumAOptional entered lower device range value.
Idevice_maxDevice range maximumAOptional entered upper device range value.
IreviewReview settingAOptional entered project comparison setting.
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Motor overload setting worksheet calculator technical guide

Estimate a motor overload setting worksheet value for Australian motor records from entered full-load current, service factor, setting percent and device range assumptions.

Use this page when a motor record needs an overload worksheet value from user-entered current and setting assumptions. The calculator produces a percent setting, a service-factor limit and the lower worksheet value, then compares that value with an entered device range or review setting where those values exist.

The output is a project record. It does not choose a relay, starter, protective device or product setting, and it does not reproduce controlled standards tables or manufacturer curves.

Field use cases

Practical overload worksheet use cases
Work settingReal questionUseful action from this page
Motor schedule reviewWhat worksheet value follows from the entered current and setting basis?Enter full-load current, service factor and setting percent.
Starter documentationDoes the worksheet value sit inside the documented device range?Enter both device range ends when the product record is available.
Replacement motor noteDid the current change enough to affect overload worksheet values?Keep the current source and calculated worksheet value together.
Protection handoffWhat value should be reviewed against product data?Export the worksheet record with source and comparison values attached.

The useful result depends on the source of each input. Full-load current, service factor, setting percent and device range should come from traceable motor, manufacturer, starter or project records.

Setting boundary

What the worksheet includes and excludes
AreaIncluded hereKept outside this page
Percent settingFull-load current multiplied by the entered setting percent.Creating the setting percent from standards or product rules.
Service-factor limitFull-load current multiplied by entered service factor.Confirming motor thermal capability or duty.
Worksheet valueLower of the two entered-data calculations.Device choice, relay class, trip curve or starter coordination.
Device rangeOptional entered range comparison.Product setting authority or manufacturer verification.
Review settingOptional entered project comparison value.A hidden criterion created by the calculator.

Manufacturer data, overload relay instructions, current standards, project specifications, local authority requirements and DNSP conditions can override the worksheet value.

Result interpretation

Reading the overload worksheet
Result stateWhat it meansPractical response
Overload recordNo device range or review setting was entered.Treat the result as a worksheet value only.
Within entered rangeThe worksheet value sits inside the entered comparison values.Keep the current source, device range and setting basis with the record.
Review entered basisThe worksheet value is outside the entered range or above the review setting.Recheck motor current, service factor, setting percent, device range and source documents.

The result is intentionally narrow. It helps expose the arithmetic basis before a person reviews device data and project requirements.

Formula basis

The worksheet first calculates the entered percent setting:

Ipercent = IFLC x setting_% / 100

It also calculates the service-factor limit and worksheet value:

Iservice_limit = IFLC x service_factor
Iworksheet = min(Ipercent, IFLC x service_factor)

When optional comparison values are entered:

Irange_low_margin = Iworksheet - Idevice_min
Irange_high_margin = Idevice_max - Iworksheet
Ireview_margin = Ireview - Iworksheet

The formula uses values entered by the user. It does not create product data, setting criteria or project requirements.

Worked records

Overload worksheet examples
Recorded situationCalculation basisExample resultFollow-up supported
Pump worksheet30 A FLC, 1.15 service factor and 115 percent setting.Percent setting and service-factor limit are both 34.5 A.Compare against documented device range and review setting.
Fan record18.5 A FLC, 1.0 service factor and 110 percent setting with no device range.Worksheet value is 18.5 A.Keep as an arithmetic record until product data is available.
Range review50 A FLC, 1.05 service factor, 125 percent setting and 40-50 A device range.Worksheet value is 52.5 A, above the entered range.Recheck current basis, range source and product documents.

Australian context

The page uses Australian 230/400 V, 50 Hz motor-circuit context, metric records and local project terminology. It names AS/NZS 3000 only as installation context and does not reproduce controlled standard tables, product settings or manufacturer curves.

Overload work can be affected by current standards, state or territory obligations, local authority requirements, DNSP conditions, project documentation, equipment ratings, duty cycle, ambient conditions and manufacturer instructions. Keep the exported worksheet beside the source documents.

Stop points

  • The motor full-load current source is unknown.
  • The service factor or setting percent is a placeholder but is being treated as product data.
  • Only one device range endpoint is documented.
  • The worksheet value is outside the entered device range.
  • Manufacturer instructions or project requirements conflict with the entered values.
  • The result is being used as product setting authority rather than a worksheet record.

Pump overload worksheet

A pump schedule records 30 A motor full-load current, a 1.15 service factor and a 115 percent worksheet basis.

Motor reference
PMP-OL-1
Full-load current
30 A
Service factor
1.15
Setting percent
115%
Device range
28 A to 40 A
Review setting
36 A
  1. Percent setting34.5 A
  2. Service-factor limit34.5 A
  3. Worksheet overload setting34.5 A
  4. Range low margin6.5 A
  5. Range high margin5.5 A
  6. Review margin1.5 A
Worksheet overload setting34.5 A

Carry the worksheet value forward with the entered current and device basis.

The worksheet setting sits within the entered device range and below the entered review setting. Keep the source values with the record.

  • Full-load current is entered from motor or project data.
  • The service factor is entered by the user.
  • Device range and review setting are entered comparison values.

Fan record without device range

A fan worksheet records an overload-setting estimate before a device range or review setting has been entered.

Motor reference
FAN-OL-2
Full-load current
18.5 A
Service factor
1
Setting percent
110%
Device range
Not entered
Review setting
Not entered
  1. Percent setting20.35 A
  2. Service-factor limit18.5 A
  3. Worksheet overload setting18.5 A
Worksheet overload setting18.5 A

Carry the worksheet value forward with the entered current and device basis.

The result is an overload worksheet record only. Add real device data before carrying the row into protection work.

  • The percent setting is entered by the user.
  • No device range was entered.
  • No review setting was entered.

Replacement motor range review

A replacement motor worksheet checks an entered overload basis against a documented device range and review setting.

Motor reference
MTR-OL-9
Full-load current
50 A
Service factor
1.05
Setting percent
125%
Device range
40 A to 50 A
Review setting
51 A
  1. Percent setting62.5 A
  2. Service-factor limit52.5 A
  3. Worksheet overload setting52.5 A
  4. Range low margin12.5 A
  5. Range high margin-2.5 A
  6. Review margin-1.5 A
Worksheet overload setting52.5 A

The worksheet value needs review against entered comparison values.

The worksheet value is above the entered device range and review setting, so the current basis and device data need review.

  • The device range is entered from source data.
  • The review setting is an entered comparison value.
  • The worksheet does not model device curves or starter behaviour.