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The specific difference between high voltage soft starter cabinet and low voltage starter cabinet
What is the specific difference between high voltage soft starter cabinet and low voltage starter cabinet


So now let's explain the difference between the high-voltage soft-start cabinet and the low-voltage starter. What we want to explain here is that high-voltage means that it is high-voltage when it reaches a certain kilowatt. For example, more than 3 kW belongs to high-voltage, low-voltage, and no A kilowatt is a low pressure.


High Voltage Soft Start Cabinet


The main circuit of the high-voltage soft starter cabinet adopts thyristor, and the voltage is raised by gradually changing the conduction angle of the thyristor to complete the starting process. This is the basic principle of the soft starter. Zhenghan Electric soft starter cabinet has many products in the low voltage soft starter market, but there are still relatively few high voltage soft starter products.


The basic principle of high-voltage soft starter is the same as that of low-voltage soft starter, but compared with low-voltage soft starter, high-voltage soft starter has its particularity in some places:


1. The high-voltage soft-start cabinet works in a high-voltage environment. The insulation performance of various electrical components must be good, and the anti-interference ability of electronic chips must be strong. When the high-voltage soft starter cabinet forms an electrical cabinet, the layout of electrical components and the connection with the high-voltage soft starter and other electrical equipment are also very important. There are still many things to pay attention to here.


2. The high-voltage soft-start cabinet must have a high-performance control core, and the soft-starter can process signals in a timely and fast manner. Therefore, this control core generally adopts a high-performance DSP chip, rather than an ordinary single-chip microcomputer chip of a low-voltage soft starter. The main circuit of the low-voltage soft starter consists of three groups of anti-parallel thyristors. In the high-voltage soft starter, due to the insufficient withstand voltage capability of a single high-voltage thyristor, multiple high-voltage thyristors must be connected in series to divide the voltage. However, the performance parameters of each thyristor are not completely consistent.


The inconsistency of the thyristor parameters of the soft starter cabinet will lead to inconsistent turn-on time of the thyristor, which will lead to the damage of the thyristor. Therefore, in the selection of thyristors, it is necessary to ensure that the thyristor parameters of each phase are as consistent as possible, and the component parameters of the RC filter circuit of each phase thyristor are as consistent as possible.


3. The working environment of the high-voltage soft starter cabinet is susceptible to various electromagnetic interference, so the transmission of the trigger signal must be safe and reliable. In the high-voltage soft starter, the trigger signal is generally transmitted by optical fiber, which can effectively avoid various electromagnetic interference.


There are also two ways to transmit signals through optical fibers: a multi-fiber method and a single-fiber method. The multi-fiber mode means that each trigger board has one optical fiber; the single-fiber mode means that each phase has only one optical fiber, and the signal is transmitted to one main trigger board, and then the main trigger board is transmitted to other trigger boards of the same phase. Since the loss of each optical fiber optical transmission process is not consistent, the single fiber method is more reliable than the multi-fiber method in terms of trigger consistency.


4. The high-voltage soft starter has higher requirements for signal detection than the low-voltage soft starter. There is a lot of electromagnetic interference in the environment where the high-voltage soft starter is located, and the vacuum contactor and vacuum circuit breaker used in the high-voltage soft starter will generate a lot of electromagnetic interference during the breaking and closing process. Therefore, not only hardware filtering, but also software filtering should be performed on the detected signal to remove interfering signals.


5. After the high-voltage soft-start cabinet completes the startup process, it is necessary to switch to the bypass operation state. How to smoothly switch to the operation state is also a difficulty for the soft starter. How to select the bypass point is very important. The bypass point is early, and the current surge is very large, even under low voltage conditions, it will cause the circuit breaker in the three-phase power supply to trip, and even damage the circuit breaker. The danger is even greater under high pressure conditions. The bypass point is late, and the motor shakes badly, which affects the normal operation of the load. Therefore, the hardware detection circuit of the bypass signal must be very accurate, and the program processing must be just right.