S94P01C -e1
35
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 cancelled in the equation above leaving only
Amps (A). We would have to use another conversion factor if the numerator and
denominator had different force x distance units.
Nominal Bus Voltage (Vbus)
The Nominal Bus Voltage can be calculated by multiplying the Nominal AC mains
voltage supplied by 1.41. When using a model with the suffix “S1N” where the
mains are wired to the “Doubler” connection, the Nominal Bus Voltage will be
doubled.
Example:
If the mains voltage is 230VAC, Vbus = 230 x 1.41 = 325V
This value is the initial voltage for the drive and the correct voltage will be
calculated dynamically depending on the drive’s incoming voltage value.
Rotor Moment of Inertia (Jm)
From motor manufacturer or nameplate.
Note
Round the calculated result to 3 significant places.
Maximum Motor Speed in RPM
This is also listed as “Speed @ Vt” (motor speed at the terminal voltage rating). The
maximum motor speed will typically be a round even value between 1000 and 6000
RPM.
Number of Poles
This is a positive integer number that represents the number of motor poles, normally
2, 4, 6 or 8.
