Regarding the allowable start button for electrical (motors), to which circuit in the electrical system is the instrument signal connected, and how is it implemented...
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As the title suggests: Regarding the allowable start button for electrical (motors), to which circuit in the electrical system is the instrument signal connected, and how is this achieved? 1. Should it be connected to the secondary start-up circuit? How is it achieved to allow startup? 2. Is the hardware related to the start button located inside the distribution cabinet? Is it just a relay?
Generally, for large motors, there should be an allowable start signal. Allowing startup is subject to certain conditions, such as pressure, temperature, liquid level, valve opening degree, and so on. These conditions are of an AND/OR nature, and it is necessary to determine them in consultation with the equipment and manufacturing processes. But it is always connected to the control loop. This process is implemented using an intermediate relay. Simply send the designated terminals to the electrical control cabinet via cables; the rest is handled by the electrical team.
First of all, I don’t understand what you mean by allowing startup – who is allowing whom? In terms of electricity, it is considered ready when a status signal is sent to the DCS from their own secondary circuit. It is very rare for a direct connection to be made to the DCS; in the case of instruments, this is referred to as interlock, and essentially it involves connecting the normally closed contacts in the secondary circuit to the DCS.
1. In terms of electricity, it is permissible to refer to this as being ready, that is, on-site/locally, usually within their own secondary circuits. Start/stop on-site, or start/stop via remote DCS. 2. The 24V relay coils in the power distribution switchgear are controlled via the DCS DO signal, thereby enabling the buttons for starting/stopping the electrical equipment (motors).
This post was last edited by fjw3081585 on 2019-5-20 08:43. The term \"allow start signal\" refers to a signal sent by the instrument; it is the signal from the instrument that enables the electrical system to operate. For example, when all the pressure requirements in the lubrication pipeline are met, the DCS sends a signal to the electrical system indicating that start-up is allowed, and only then does the start-up indicator light on the high-voltage cabinet come on, allowing the electrical system to start up. It shouldn’t be the electrical supply powering the instrument, right? My understanding is that when the several parameters specified by the process meet the required conditions, the DCS sends signals to the various DI points in the electrical system (referred to as DI by the DCS side); these signals then go to the electrical system’s secondary control circuit, allowing the motor to start. It is the instrumentation that controls the electrical system, and the goal is to ensure that the process parameters are met before the motor can be started. For example, before starting a large compressor, it is necessary to check the condition of the lubricating oil; this is done by using three pressure transmitters located on the lubricating oil main pipeline. For interlock purposes, I recall that a 3-out-of-2 voting system is used, and only when the conditions are met is a signal allowing startup sent to the electrical control system.
It’s placed in the distribution cabinet; it’s probably a contactor circuit.
This is a limitation caused by your limited exposure to devices. It is correct that the instrument has a start-up signal. Some large electrical equipment also has its own start-up signal, such as high-voltage motors. And it has a name called Beiduo.
Do you mean by the preparation signal for the DCS that it refers to the situation where the transfer switch is set to the remote position? The standard process also deals with that thing called a remote control switch, right?