Locked Rotor Current vs. Starting Current

Only time.

Motors start at locked rotor current, but that quickly decreases.

TVP45 is correct but it is true only for DOL stating method.

Here is more detail:

Locked Rotor Current: It is current drawn by the motor when the motor rotor is locked (stopped) but full voltage is applied to the motor terminal.

Starting Current: It is the current drawn by the motor at the time of motor starting period. In the case of the DOL starting, the full voltage is applied on motor terminal with the rotor stopped. For the first few seconds, the rotor is almost stopped and it is the similar to the case of locked rotor condition. So, the starting current drawn by the motor is same as the locked rotor current for DOL start. For other starting methods, the lower voltage is applied to the motor terminal and hence the starting current is less than the locked rotor current.

Hope, it helps.

- MS

GENERAL INFORMATION Manufacturer AUMA Model No. SA10.1-125-GK14.2(4:1)-F14 Rated Output Torque (ft-lb) or (Nm) 400Nm Factory Torque Switch Settings Open N/A Close N/A Torque Close Seating Required for This Application (Yes/No) Yes Speed of Operation 31.25RPM Open to Close (sec) 75 Close to Open (sec) 75 Maximum Differential Pressure Which Actuator is Capable of Operating Against (psi) or (Pa) 660Psi Valve Stem Diameter (in.) or (mm) 36mm Thrust Allowance for Valve Packing Friction Weight (lb) or (N) N/A Gear Housing Material Cast Steel Self-Locking Gearing (Yes/No) Yes MOTOR DATA Manufacturer AUMA Enclosure/Cooling Rating IP67 Class F Horsepower/rpm or kW/rpm 1.5 KW 2800rpm Voltage/Phase/Hz 400 3P 50HZ Full Load Current (amps) 4.0 Locked-Rotor Current (amps) 5.5 Load Current for Setting Overload Relay Protection (amps) 5.5 Starting Current (amps) 16 Motor Time Rating at Maximum Driven Equipment Torque in a 50° C Ambient (minutes) S2-15min Motor Space Heater (watts/volts) N/A N/A Are Motor Self-Reset Thermal Switches, if Provided, Required to be Wired in Purchaser's Starter Coil Circuit? (Yes/No/Recommended) Yes CONTROLS DATA Enclosure Rating IP67 Network Communications, if Applicable N/A Enclosure Space Heater (watts/volts) 5W 115VAC Integral Starter (Yes/No) Yes DRAWINGS Item Drawing Title Drawing Number Revision Outline Diagram SA10.1-AM-GK14.2 SA10.1-GK14.2 Dated 2009.3.12 Schematic/Wiring Diagram Three-Phaase Matic Interface(without position feedback) MSP:1A10KC5-H18E1 KMS TP110/201 Dated 2009.3.12

Or,

They are the same values, but Start current occurs at startup, Locked Rotor occurs any time power is applied and the motor cannot spin, i.e. a load jams.

Locked rotor current is the current absorbed after a period of 3 secs,during which time no movement of the stator has ocurred and no drop in applied nominal supply voltage.Typical test for LRA figures on refrigeration compressors.

To differentiate simply,

Starting Current subsidesas the motor accelerates to its rated speed, whereas the locked rotor current doesn't.