Technical terms

Explanation of Symbols

From Rated Voltage to Rotor Inertia. An overview of our common symbols, descriptions and definitions:


Symbol	Description	Definition	Unit
V_N	Rated Voltage	Voltage for which normal data are valid	V
k_E	Voltage Constant	Ratio between induced voltage and angular velocity with motor driven as a generator	mV/r.p.m.
R_m	Speed Regulation Constant	Ratio between no load speed and stall torque	r.p.m./ mNm
t_E	Electrical Time Constant	Time required to reach 63% of final value of current in locked rotor condition	ms
t_M	Mechanical Time Constant	Time required to reach 63% of speed under no load condition with rated voltage applied	ms
R_th1 R_th2	Thermal Resistance	Characteristic value of thermal transfer resistance. (No additional heat sink, locked rotor.)	K/W
k_t	Torque Constant	Ratio between generated torque and motor current	mNm
R	Terminal Resistance	Mean value of ratio between rated voltage and stall current	Ohms
I_S	Stall Current	Ratio between applied voltage and terminal resistance	A
I_O	No Load Current	Current under no load condition at rated voltage	A
I_N	Rated Current	Current under rated load at rated voltage	A
P_out	Rated Output Power	Mechanical power at rated torque and rated speed available at motor shaft	W
P_{out max}	Maximum Output Power	Maximum mechanical power at rated voltage. (Normally not applicable for continuous running)	W
T_N	Rated Torque	Torque at rated output power available at motor shaft	mNm
T_S	Stall Torque	Torque at rated voltage with the motor shaft stalled	mNm
n_N	Rated Speed	Speed at rated voltage and rated torque	r.p.m.
n_O	No Load Speed	Speed at nominal voltage under no load condition	r.p.m.
h_N	Rated Efficiency	Ratio between rated output power and rated input power	%
P_in	Rated Input Power	Product of rated voltage by rated current	W
J_R	Rotor Inertia	Mass moment of inertia of rotor	gcm²