company news

1. Select soft starter

Note whether the load is standard or heavy. Different types of starters are selected according to different load properties.
If the load is a centrifugal pump (fire pump, spray pump, water pump, etc.), it is necessary to use the pump control function to reduce the occurrence of system water hammer caused by liquid flow impact when starting and stopping. Therefore, it is necessary to use a soft starter with pump control function, such as another one with under load protection or phase reversal protection;
If the load is a fan, the soft start function can be used to reduce the belt wear and mechanical impact, and the braking torque function can be used when stopping;
The load is blender, crusher, hoist, etc., using double slope starting and preset low speed operation to avoid mechanical damage;
The load is the conveying equipment, which can use the soft start and preset low speed function to realize smooth start-up and stop. The soft stop eliminates the anti inertia impact of the drag system caused by free stop, and avoids product displacement and liquid overflow;


2. The starter is selected according to the nominal power, current and load property of the motor.

Generally, the capacity of the soft starter can be slightly greater than the working current of the motor. When some heavy loads are applied in the cement plant, the first gear should be increased, such as crusher, ball mill, elevator, long belt, mixer, fan, etc., and the heat dissipation factor should be properly considered.

3. In other aspects, we should also consider whether the protection function is complete.


Such as over-current protection, over-voltage protection, single grounding protection, upper and lower open phase protection, three-phase imbalance protection, phase reversal protection, etc. Without overload protection, it must be protected by another heating relay.
Some soft starters generally do not have short-circuit protection, need to add fast fuse and match with the thyristor capacity, it can make the thyristor be protected in the case of short-circuit when connecting the load, low-voltage circuit breaker generally can not protect the soft starter. When several starters are connected to the same power supply, it is recommended to use the incoming reactor.
Special attention should be paid to the wiring from the soft starter to the motor, most of which are 3 outgoing lines, but some products also have 6 outgoing lines. The soft starter can be installed in the system with power factor compensator, but the capacitor must be located on the side of the power line of the soft starter to avoid the damage of the thyristor of the soft starter due to the discharge of the capacitor. In addition, an inductive coil is connected between the power supply and the capacitor. Most of the soft starters are equipped with auxiliary contacts for normal operation and fault signals, which can be used in engineering design.
The soft starter is allowed to operate under rated load condition for a long time. The bypass contactor can be used to short circuit it after starting. After removal, pay attention to whether the motor running circuit has overload thermal protection function. In practical application, if the process conditions permit, when starting multiple motors with one soft starter, its capacity should be considered according to the maximum starting load of the motor, which can greatly save the investment cost.