Siemens 7SR105 Rho User Manual page 179

Generally the relay thermal setting calculation is carried out in the following order:-
Where available:
Rated output
Rated Voltage
Rated Frequency
Rated Power Factor
Rated Efficiency
Service Factor
Stall Withstand Time Cold/Hot
Starting Method
Locked Rotor Current
Permitted starts cold/hot
Start Time @ 100% Voltage
Max. Starts Per Hour
Min. Time Between Starts
Control Device
CT turns ratio (T)
VT Ratio and connection
NPS Weighting
Thermal Overload Setting (49 Itheta)
Motor Start Current (x Itheta)
Motor Stop Current (x Itheta)
Overload: OL protection settings, alarms and inhibits
Stall protection settings
Start protection settings
Current Unbalance protection settings
Figure 2-2
©2018 Siemens Protection Devices
Motor Rating Plate or Data Sheet Information
CT and VT Connection Details
Nominate Basic Thermal Settings
Calculate Thermal Protection Settings
Enable and Set Other Protections as Required
Summary of Protection Settings Calculation Procedure
7SR105 Rho and 7SR17 Rho Applications Guide
kW
kV
Hz
% (95% default)
secs
A primary
Chapter 7 Page 6 of 31