Regarding the issue of the number of control consoles for 24V power supplies
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May I ask, for a power supply of 220V to 24V, how many instruments can generally be driven by 3A? And how should the capacity be calculated when designing it? For example, there are valves, transmitters, radars, tuning forks, and temperature transmitters on site. There are 10 switch valves, 4 temperature transmitters, 4 pressure transmitters, 2 radars, and 1 mass flow meter on site – is a 3A power supply sufficient?
The solenoid valve for the on/off valve has a power consumption of around 11 watts, while the instrument consumes about 5 watts; estimate this roughly and leave some margin.
For this, you need to examine the power consumption of the instruments when they are operating normally; it’s essential to leave a margin, such as 20%, as even without any load, the power supply will still experience reduced lifespan
This post was last edited by Allen-80 later on 2018-1-19 at 09:11. The power supply is 24V, with a current of 3A; thus the power is 72W. For the solenoid valves used to control the flow, low-power versions should be chosen, with a power consumption of around 4W each. For 10 such valves, the total power consumption will be 40W. As for the temperature transmitters, it’s necessary to check the manual – intelligent models probably have low power consumption, with each one consuming no more than 1W. Radar and mass flow meters, on the other hand, tend to have higher power consumption. Since the power supply is 24V, both the radar and mass flow meters will also operate at 24V. Based on this voltage, the power consumption seems reasonable; however, the exact values need to be confirmed by referring to the manual. As a rough estimate, it should be similar. It’s also important to determine what current rating the switch at the higher level should have; if possible, it’s advisable to choose a switch with a slightly higher current rating. This is just a suggestion for reference. As a supplementary note, temperature and pressure transmitters can utilize loop power supply, so it should not be included in the external power supply calculation.
1. Regarding the power supply for instruments, safety is a concern; they need to be isolated from each other—sometimes when instruments share the same power supply, signal interference can occur. 2. For 2-wire 4–20mA instruments, the power consumption can be estimated at 25mA or 30mA; as for other devices, the power level depends on what is specified in their technical documentation. 3. Considering heat generation, power supplies are generally used, and it’s unlikely that anyone would use more than half of the maximum power allowed
This post was last edited by budaoweng123 on 2018-1-19 at 13:29. Rosemount radars generally consume around 15W. There are 4 temperature transmitters and 4 pressure transmitters; these are definitely two-wire instruments, with power supplied through the instrument channels, so no separate power supply is required
You need to determine yourself the power consumption of the instruments in this power supply circuit, and include a certain margin to ensure that the instruments can operate properly. Asking in this way won’t yield an accurate result; you should count it yourself using your on-site data.