Regarding the motor start/stop signals and interlock shutdown signals, why can’t they be displayed on the inverter?

1. For variable-frequency motors, when the motor control panel is not in the closed position, it should indicate a stopped state (red), but it shows green instead. When questioned regarding the meter and electrical components, it was stated that the frequency converter is connected. I guess “green” represents the signal that the inverter is powered on. However, powering on the inverter does not mean that the motor will start running; the inverter needs to receive a \"start\" command (such as from a button on site) before it can supply power to the motor. The final step is to set the speed of the inverter, after which the motor will actually begin to rotate. Regarding the start/stop signal for the variable frequency motor, should it be the signal from the main motor, the on/off signal from the control circuit of the operation panel, or the signal from the inverter? ? In addition to obtaining the \"powered\" status signal from the inverter, it is also necessary to get the \"speed feedback signal\" – that is the truly important one; all other signals are merely supplementary. How to display the motor’s start/stop signals correctly? It is required to maintain synchronization with the field; if the motor is not rotating, the DCS should display a red color. Similar to a single-loop regulator (comparable to an inverter), it requires 220VAC power supply, and its AO output is used to control the control valve. To prove that the valve is open, you need to check the current value of AO; even if there is a current of, for example, 4 mA, the valve remains closed. The most reliable method of measurement is to install a separate speed measurement probe on-site, similar to installing a valve position feedback transmitter. 2. For motors that are involved in interlocking, such as those that stop as part of an interlocking mechanism, pulse signals are generally used. Does the motor stop when the relay is closed or when it is opened? Why is it common for the motor to stop after 5 seconds with the relay in the closed state? How is this stoppage achieved in the electrical circuit? For low-voltage electrical equipment, to stop its operation and to disconnect the power supply, the \"stop button\" on the on-site control panel is used; this button also serves to stop the pump. For high-voltage electrical equipment, when operation is stopped and an electric signal indicating a \"closed\" state is required, the \"stop button\" on the on-site control panel is also used to shut down the pump. If the instrument does not command the electrical system to stop the pump using the above signals, then a changeover relay must be added in the electrical circuit; its contacts need to be reversed and connected to the electrical control circuit in order to stop the pump. 3. How is the operating status of the motor determined? ? Thus, the operation signals indicated in red and green in the DCS are derived from the electrical contactor KM; as long as it is powered on and closed, the motor on site is energized and starts up. @jiaguoyun

Generally speaking, the operating status of electrically driven equipment and the electrical parameters of key pumps are transmitted via RS485 communication to the DCS for display. The operating status of the pumps involved in interlocking is displayed in the DCS through hardwired connections. The reality is as follows: 1. For variable-frequency motors, when the motor control panel is not in the closed position, it should display a stop status (in red), but it shows green instead. When questioned regarding the meter and electrical components, it was stated that the frequency converter is active. So, for the start/stop signals of variable-frequency motors, should it be the signal from the main motor, the signal from the control circuit of the control panel, or the signal from the frequency converter? ? How to display the motor’s start/stop signals correctly? It is required to remain in sync with the field; if the motor is not rotating, the DCS should display a red color, indicating that it is powered on but not operating. The start/stop signal is a variable-frequency signal. 2. For motors that are involved in interlocking, such as those that stop as part of an interlocking mechanism, pulse signals are generally used. Does the motor stop when the relay is closed or when it is opened? Why is it common for the motor to stop after 5 seconds with the relay in the closed state? How is this stoppage achieved in the electrical circuit? Disconnect. This is small signals controlling large signals. 3. How is the operating status of the motor determined? ? Is that why red and green are used as indicators in DCS? In the case of contactors, a current transmitter is used to capture the current signal and convert it into a 4-20mA signal that is sent to the DCS; this allows for the monitoring of the motor current and thus an understanding of its operating status.

Issues with the motor’s start/stop signals and interlock shutdown signals – why can’t they be displayed on the inverter?

1. How is the speed of an inverter set? 2. For a low-pressure (high-pressure) motor running at 2900 revolutions per minute, what speed is considered to indicate that the motor has started?

1. How is the speed of an inverter set? Basically, it works like this: the speed range is set on the frequency converter, for example 0–3500; the corresponding signal output from the frequency converter is 4–20mA, and the DCS is configured to reflect this range of 0–3500. As for the frequency, that is part of the setting process for the inverter. If there is a pump and a gearbox, the full-scale speed displayed by the DCS = 3500/(gear ratio). 2. For a low-pressure (high-pressure) motor running at 2900 revolutions per minute, what speed is considered to indicate that the motor has started? I think \"what speed is acceptable.\" . . ”It doesn’t really matter, as the motor won’t operate at very low speeds once it starts up. Moreover, variable-frequency motors usually come equipped with an ammeter on their control panel, so checking that ammeter is sufficient. One more thing to note: when the SIS is shut down, the main power supply to the inverter is usually cut off; the inverter can be put back into operation only after it is reset ； The start/stop signal is sent to the input port of the inverter; it does not cut off the main power supply, only starts or stops the motor. @jiaguoyun

Still don’t understand:dizzy: Are there any illustrations? ? ? ?

3. How is the operating status of the motor determined? ? Is that why red and green are used as indicators in DCS? This comes from the motor contactor KM; generally, the normally open auxiliary contact is used, and it is a dry contact signal that does not require conversion to current or anything similar. Add a relay here near the instrument to isolate the DI card connected to the DCS.

1. For variable-frequency motors, when the motor control panel is not in the closed position, it should display a stop status (in red), but it shows green instead. Upon asking the instrumentation and electrical staff, they replied that the frequency converter is connected. So, for the start/stop signals of variable-frequency motors, should it be the signal from the main motor, the on/off signal from the control circuit of the control panel, or the signal from the frequency converter? ? The difference between an inverter and a power-frequency motor is that a power-frequency motor starts up as soon as it is powered on, meaning it begins to rotate immediately. In contrast, with an inverter, rotation only occurs after the speed has been set. In my opinion, the DCS display should indicate the power-on status of the main motor through a change in color; if process operators keep getting confused by issues related to red or green colors or whether rotation is occurring on-site, this can be resolved through training. It cannot be assumed that a red display necessarily means the electrical equipment is not powered. How to display the motor’s start/stop signals correctly? It is required that the display should match the actual situation on site; if the motor is not rotating, the DCS should show a red color. Similarly, if such a display is necessary, the color change signal can be set so that the display turns green when both the motor receives power and the frequency conversion reaches the lowest speed. 2. For motors that are involved in interlocking, such as those that stop as part of an interlocking mechanism, pulse signals are generally used. Does the motor stop when the relay is closed or when it is opened? Why is it common for the motor to stop after 5 seconds with the relay in the closed state? How is this stoppage achieved in the electrical circuit? If the relay closes, the output circuit takes the normally closed contact; this normally closed contact then becomes a normally open contact that connects to the main circuit of the electrical device KM, thereby breaking the device’s self-protection circuit and allowing it to stop operating. 3. How is the operating status of the motor determined? ? Is that why red and green are used as indicators in DCS? Take the auxiliary contacts of the contactor, which are dry contacts, and connect them to the DCS system; a relay can be used at the DCS side for isolation

I’m not sure how many different types of frequency converters your factory has. If there are many different types, it’s not recommended to use communication methods; hard wiring is more reliable.