- General Support
- Oneline & User Interface
- License Key Issues
- Downloading/Installing Software
- Printing
- Reports
- Equipment Modeling
- DAPPER (Demand Load)
- DAPPER (Load Flow)
- DAPPER (Short Circuit)
- CAPTOR (TCC)
- Arc Flash Evaluation
- Equipment Evaluation
- Cable Ampacity
- A_Fault (ANSI)
- IEC 60909 Fault
- IEC 61363 Fault
- TMS (Transient Motor Starting)
- HI_WAVE (Harmonics)
- Unbalanced/Single Phase
- DC Systems Analysis
- GroundMat
- Cable-3D
- Scenario Manager
- Backup & Import/Export

# What is the Starting PF to be entered for Motors?

The IEEE Brown book (Std 399) suggest that Motors under 1000 hp, have a typical PF=0.20, and Motors 1000 hp and over, have a typical PF=0.15. The Brown book also state that the starting power factor can be calculated by knowing the short-circuit X/R ratio of the machine.

Starting power factor = cos (arctan X/R).

In PTW, the above equation is used in generating the starting PF. The default X/R is 10, which will then result to a PF = 0.0995.

These power factor values are only rules of thumb, thus the actual power factor should always be confirmed with the manufacturer.

Starting power factor = cos (arctan X/R).

In PTW, the above equation is used in generating the starting PF. The default X/R is 10, which will then result to a PF = 0.0995.

These power factor values are only rules of thumb, thus the actual power factor should always be confirmed with the manufacturer.