Everybody knows the star-delta starting method, which you can assemble with your own hands ’. The scheme has many drawbacks and extremely adversely affects the “life” of the windings. As is known, this is influenced by the overheating of the windings from a large starting current. 2 relays are used to switch from star to delta, and the controller is also used to trigger these relays. According to the experience of operating automated lines in production, it can be said that the engines very often fail from direct connection to the network. Therefore, you need to use a soft start circuit.
However, the new soft starters for asynchronous motors and frequency drives can operate with a single star-winding circuit and change the speed of rotation with frequency. Advantages: the user had to deal with the same asynchronous motor running on the relay circuit of the direct start of the electric motor and after replacing the relay with frequency drive Yaskawa A1000. After replacing the engine works smoothly and smoothly, mechanical faults are instantly determined and the drive gives an error. No overheating of the motor. Start was smooth with uniform acceleration.
- 1 Drive Parameters for Soft Start Setting
- 2 Ways to configure the device
- 3 Ways to prevent the engine from stopping
- 4 A number of manual engine parameters
Drive Parameters for Soft Start Setting
This device is implemented 3 possible control modes. Select the appropriate soft start control method for the task.
Frequency control for asynchronous motors, general variable speed applications, especially useful to start several electric motors from one device and when replacing the drive when the parameters unknown.
Frequency control with feedback on the speed of the pulse generator, for general-purpose applications that do not require high dynamic characteristics, but require high accuracy in speed. This mode should be used if the parameters of the motor scheme are unknown and autotune cannot be performed.
Open loop vector control. Common applications with variable speed. Applications requiring control with high accuracy and high speed.
Closed-loop vector control. For general variable speed applications requiring high precision speed control down to zero, fast torque increase or precision torque control. A feedback signal for engine speed is required.
The drive can operate in two modes: normal and heavy. In normal mode, the device can withstand overload by 120% for 60 seconds, this is used in applications where torque increases with increasing speed (these are fans and pumps). In heavy mode, the device can withstand overload up to 150% for 60 seconds, it is used in applications where there are high loads, where the torque is constant (these are extrusion presses, conveyors, cranes and other).
In the drive settings there are soft start parameters, there is four sets of acceleration and deceleration periods engine, which can be set in the parameters. If necessary, S-curves can be activated, for a smoother start and end of the acceleration deceleration.
Ways to configure the device
Also in the parameters of the device there is a possibility to choose the way to prevent a stop during acceleration. (In this article we consider general information about the capabilities of the frequency drive, more detailed information about the parameters you can get from the user manual). The first method is common.. Acceleration stops when the current exceeds the setpoint. The second way is intellectual. Acceleration for the shortest possible time without exceeding the engine stop prevention level during acceleration.
The device has a choice of how to prevent the engine from stopping during braking:
- The first method is common. Braking ceases as soon as the DC bus voltage exceeds the stop prevention level.
- The second way is intellectual. Maximum fast braking without failure due to overvoltage.
- The third way is to prevent the motor from stopping with a brake resistor. The engine stop prevention during braking is activated in coordination with dynamic braking.
- The fourth method is braking when working with overexcitation. Braking occurs with increasing flux density of the magnetic field of the electric motor.
- The fifth method is braking when working with overexcitation 2. The braking speed is adjusted according to the DC bus voltage. The sixth method - slows down the regulation of the speed of braking in accordance with the output current and voltage of the DC bus.
To set the required parameters The device uses automatic tuning of the asynchronous motor. Ways to tune the engine: the first is a stationary setting for interphase resistance; the second is rotational auto tuning for frequency control ( necessary for the operation of energy saving functions, speed estimation and speed search); the third is inertial tuning (before inertial tuning it is necessary perform rotational adjustment); the fourth is setting the ASR gain (before setting up with your own hands, you must perform a rotational autotuning).
Ways to prevent the engine from stopping
Choosing a way to prevent engine stall during braking.
- Prevent engine stalling using a brake resistor. The prevention of motor stall during braking is activated in coordination with dynamic braking.
- Braking when working with overstimulation. Braking occurs with increasing flux density of the magnetic field of the engine.
- Braking when working with overexcitation 2. The braking speed is adjusted according to the DC bus voltage. Enabled. Slows down regulation of the braking speed in accordance with the output current and voltage of the DC bus.
Choosing a Stop Prevention Method during work:
- The first one is deceleration time off. The drive operates at a given frequency. High loads can cause a loss of speed.
- The second is braking time. The braking time given by parameter C1-02 is used along with measures to prevent the engine from stopping. 2: Braking time 2. The deceleration time specified by parameter C1-04 is used along with measures to prevent stopping.
Also set the level to prevent the engine from stopping during operation, 100% level is equal to the rated drive current.
A number of manual engine parameters
- The rated power of the motor indicated on the nameplate.
- The rated voltage indicated on the nameplate.
- The rated current indicated on the nameplate.
- Fundamental frequency. Sets the nominal frequency indicated on its nameplate.
- The number of poles of the engine. Sets the number of poles shown on its nameplate.
- Speed constant. Sets the nominal speed indicated on the nameplate.
- The number of pulses per revolution of the pulse generator. Sets the number of pulses per revolution for the pulse generator used (pulse generator or encoder).
- Idling current (stationary auto-tuning). Sets the no-load current. After setting the power to T1-02 and the rated current to T1-04, this parameter will automatically display the no-load current for a standard 4-pole Yaskawa motor. Introduces no-load current as specified in the test report.
- Nominal motor slip (stationary auto tuning). Sets the nominal slip. After setting the motor power to parameter T1-02, this parameter will automatically display the slip for the standard 4-pole Yaskawa motor. Enters slip as indicated in the engine test report.
- Engine loss in steel. Sets loss in steel to determine energy efficiency. This value is given by the set of parameters E2-10 (engine loss in steel) during cyclic change of power. When parameter T1-02 is changed, the default value corresponding to the input power appears.