How does DCS control the operation of the motor? How are the control signals connected? Thank you
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For example, to start, the control signal is connected to the coil of the AC contactor; to stop, a normally closed switch is connected in series with the coil. So how are fault detection, emergency stop, and operation status indication achieved? Thank you
What kind of failure does it refer to in the event of a fault? In the case of an emergency stop, it is connected to the circuit that controls the AC contactor in the same way as a normal stop. The operation indicator DI module passes through the normally open contacts of the AC contactor; when the AC contactor closes, the feedback circuit also closes.
For example, in the case of a fault with the pump used on-site, should it be reported as a motor fault? Can the pump itself report its own faults?
If there is no built-in frequency conversion, the most reliable approach is to install a sensor on the pump to monitor it, such as a speed sensor.
Can fault signals be transmitted from a thermal relay or a motor protection device?
DCS controls the operation of motors; it is generally connected in series within the electrical control circuit. Normally, the contact is open when starting and closed when stopping. Indications for faults, emergency stops, and operational status all require coordination with the electrical team to be implemented
The start signal should be a pulse; when the coil is powered, the relay closes, and the circuit locks itself, so a normally open contact is not necessary for starting. Stopping is normally closed; a pulse signal is used to open this normally closed connection, causing the control circuit to lose power and thus the circuit to be disconnected. Contact them to learn about self-locking circuits, and you’ll understand. A fault is generally indicated by the normally closed signal of the thermal relay; when the thermal relay activates, this normally closed circuit is opened, the control circuit is interrupted, and the pump stops operating. For the remaining parameters related to the pump, such as current and temperature, the normally closed signals from the corresponding switch transmitters can be used.
The emergency stop is usually normally closed; in the case of faults and during operation, it can be either normally open or normally closed – this needs to be determined in consultation with the electrical team. It is generally a dry contact
The pump temperature can be monitored through a temperature sensor, while the gap vibration displacement of the pump shaft can be detected by a corresponding sensor; this enables functions such as alarm interlocks. For motor operation, normally the contacts are open when the motor starts and closed when it stops. Indications related to faults, emergency stops, and operational status all require coordination with electrical specialists to be implemented