| In an induction motor is a voltage that on several | | | | proportional to the torque generated and the voltage |
| (connected up to about 6 times basis) of its rated | | | | at the motor is directly proportional to the actual speed, |
| current. Since the charge is accelerated, the available | | | | while the network side, the voltage is constant, the |
| torque drops usually rises a little, then a maximum, | | | | mains current is directly proportional to the load on the |
| while the current remains high until the motor reaches | | | | engine , which the user interface or CN C, where N is |
| full speed. | | | | the torque and speed (taking into account the losses |
| In contrast, if a VFD starts a motor, applies a first low | | | | will be neglected so that in this discussion.) |
| frequency and voltage to the motor. The frequency is | | | | (A) n is the network (network) and for m motor (2) C |
| from 2 Hz or less. This will avoid such a low frequency | | | | shows the torque [Nm], the voltage U [V], that A] and |
| of the high inrush current, that occurs when the engine | | | | N [for the speed [rad / s] we neglect the losses at the |
| simply by applying the utility (mains) voltage started by | | | | moment: Un.In Um.Im = (not draw the same grid and |
| turning a switch. After starting the VFD, and increases | | | | the motor) Um.Im Cm.Nm = (= motor mechanical |
| the frequency of the applied voltage at a controlled | | | | power from the electric motor) In view of the United |
| rate or be strengthened to accelerate the load without | | | | Nations a constant voltage (will) concluded : In Cm.Nm |
| drawing too much power. This method usually begin to | | | | = / UN line that is in progress (network) is in direct |
| develop an engine to 150% of rated torque, while the | | | | proportion to engine power. |
| VFD is income of less than 50% of the rated current | | | | With a VFD, the shutdown is just the opposite, that the |
| of the power system in the low speed range. A VFD | | | | boot sequence. The frequency and the voltage at the |
| can be adjusted in order to produce a claim to 150% | | | | motor is increased at a controlled rate. If the frequency |
| torque from standstill to full speed. | | | | tends to zero, the motor stops. A small amount of |
| Note however that the engine cooling is generally not | | | | braking torque available to slow the load a little faster |
| good at slow speed. He works at low speeds, even | | | | than if it stops the engine was turned off and just let |
| with nominal torque over long periods is not possible | | | | the others. additional braking torque can be obtained |
| due to overheating of the engine. If continuous | | | | controlled by a transistor) by the addition of a brake |
| operation at high torque at low speeds requires | | | | circuit (resistance in order to dissipate the braking |
| external fan is required. Please check with the | | | | energy. With recifiers four quadrants (Active Front |
| manufacturer of the engine and / or VFD. In principle, | | | | End), the VFD is to stop the burden of applying a pair |
| the current in the side of the motor is directly | | | | of reverse and back to the mains. |