Technical terms

This chapter provides information on various technical terms and their meaning.

Standstill torque M₀ [Nm]

Torque, also referred to as starting torque, that the servo drive can generate at standstill. It can be maintained indefinitely at a speed n < 100 min^-1 and nominal ambient conditions.

Nominal torque M_n [Nm]

The torque that the servo drive delivers when it is operated at nominal speed and nominal current. Can be output in continuous operation S1 for an unlimited period of time.

Standstill current I_0rms [A]

Sinusoidal current RMS value. This is consumed at a speed of n < 100 min^-1 in order to generate the standstill torque.

Peak current / pulse current I_0max [A]

Sinusoidal peak current RMS value. The configured peak current of the servo drive used must be less or equal.

Torque constant K_Trms [Nm/A]

Indication of the torque in Nm generated by the servo drive per ampere of standstill current. The following applies: M₀ = I₀ x K_T

Voltage constant K_Erms [mVmin]

Indication of the induced servo drive EMK at 20 °C, based on 1000 rpm. This is specified as the sine RMS value between two terminals.

Rotor moment of inertia J [kgcm²]

Measure of the acceleration capacity of the servo drive. For example, at J₀ the acceleration time t_b from 0 to 3000 rpm can be calculated based on the following formula:

with M₀ in Nm and J in kgcm²

Thermal time constant t_TH [min]

Specification of the heating time of the cold servo drive under load with I₀ until an overtemperature of 0.63 x 100 Kelvin is reached. This temperature rise happens in a much shorter time when the motor is loaded with the peak current.

Release delay time / application delay time of the
brake t_BRH [ms]/t_BRL [ms]

Specification of the response times of the holding brake [+] when operated with the nominal voltage

Winding inductance L [mH]

Specification of the servo drive inductance. It is the average value for one revolution, with two energized phases, at 1 kHz. Saturation of the servo drive must be taken into account.