Lenze S94P01G Position Servo - Manual (Page 37)

S94P01G
35
Interface
4.6.3.1 Electrical constants
Motor Torque Constant (Kt)
Enter the value and select proper units from the drop-down list.
NOTE
Round the calculated result to 3 significant places.
Motor Voltage Constant (Ke)
The program expects Ke to be entered as a phase-to-phase Peak voltage. If you have
Ke as an RMS value, multiply this value by 1.414 for the correct Ke Peak value.
Phase-to-phase winding Resistance (R) in Ohms
This is also listed as the terminal resistance (Rt). The phase-to-phase winding
Resistance (R) will typically be between 0.05 and 200 Ohms.
Phase-to-phase winding Inductance (L)
This must be set in millihenries (mH). The phase-to-phase winding Inductance (L) will
typically be between 0.1 and 200.0 mH.
NOTE
If the units for the phase-to-phase winding Inductance (L) are given in
micro-henries (µH), then divide by 1000 to get mH.
Nominal phase current (RMS Amps)
Nominal continuous phase current rating (In) in Amps RMS. Do not use the peak current
rating.
NOTE
Sometimes the phase current rating will not be given. The equation
below may be used to obtain the nominal continuous phase-to-phase
winding current from other variables.
In= Continuous Stall Torque / Motor Torque Constant (Kt)
The same force x distance units must be used in the numerator and denominator in the
equation above. If torque (T) is expressed in units of pound-inches (lb-in), then Kt must
be expressed in pound-inches per Amp (lb-in/A). Likewise, if T is expressed in units of
Newton-meters (N-m), then units for Kt must be expressed in Newton-meters per Amp
(N-m/A).
Example:
Suppose that the nominal continuous phase to phase winding current (In) is not
given. Instead, we look up and obtain the following:
Continuous stall torque T = 3.0 lb-in
Motor torque constant Kt = 0.69 lb-in/A
Dividing, we obtain:
In = 3.0 lb-in / 0.69 lb-in/A =4.35 (A)
Our entry for (In) would be 4.35.
Note that the torque (lb-in) units are cancelled in the equation above leaving just
Amps (A). We would have to use another conversion factor if the numerator and
denominator had different force x distance units.