The SIS stops the pump; the relay remains powered, using its normally closed contacts, and power is cut off during pulses
Thread Content
The SIS controls the pump to stop; the relay remains powered, using its normally closed contacts. When the pulse is stopped, power is cut off and the contacts close, causing the pump to stop. Does the pump use normally closed contacts? Are the relays and the contactors for the pump connected in series? If the relay contacts are open, is there voltage present between the positive and negative terminals of the contactor with respect to ground? The actual technician only knows about the instruments.
The relay contacts are open; are contactors connected in series across the two ends? When measuring the voltage with respect to ground, is one end charged or are both ends charged?
SIS uses safety relays; the pump shutdown signal is a long signal, not a pulse signal. With pulses, the pump can still be started on-site, but with a long signal, it cannot be started after interlocking is activated.
It’s not designed yet; it’s already in use. I want to study its principle
It has been designed and is already in use
This is a bit strange. The SIS has adopted a fail-safe control mode, meaning the pump stops operating in the event of a power loss. In theory, you should connect the normally open contacts of the relay; the relay remains powered on, keeping the contacts closed, and when power is lost, the contacts open. These contacts are connected in series within the main electrical control circuit. In your case, where you’ve done the opposite, there should be another relay KA connected in series within the electrical secondary circuit; this relay is used to control the shutdown of the pump. One set of normally closed contacts of this relay KA is connected in series in the main control circuit. Under normal circumstances, this relay KA remains de-energized. However, when the SIS activates or a fault occurs, the normally closed contacts of KA open, causing the control circuit to lose power and thereby stopping the pump. If you take a closer look at the electrical secondary circuit diagrams, you’ll understand what’s going on.
Can voltage be measured when the relay in the electrical control circuit is not powered?