The fuse status signal is connected to the control system
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This post was last edited by Gentle man on 2019-1-28 at 16:58. Dear experts, the operating status of devices such as circuit breakers, contactors, and thermal relays is connected to the PLC system through their built-in auxiliary contacts. But have you ever encountered fuses, commonly known as insurance elements? How is the operating status of these fuses connected to the PLC system? ? ? It refers to connecting the signal directly from the fuse unit to the PLC, not indirectly through a relay for conversion before connection! ! If anyone knows, please give some advice! !
I can’t see the image; I haven’t heard that the insurance has been recorded in the system……
It is still done through an intermediate relay, with the auxiliary contacts being used to connect to the DCS system; this approach provides better isolation and is thus safer
Fuses, such as those located at the power supply end of the secondary control circuit, usually have a single-pole fuse connected in series to prevent short circuits in the secondary circuit. This location is therefore very important. The main switch has auxiliary contacts that indicate whether the switch is in the normal closed position; however, if the fuse in the secondary circuit fails, it prevents control commands from reaching the electrical secondary circuit. Hence, this fuse is extremely important. In modern fully automatic control systems, it is necessary to monitor the status of each key point
This post was last edited by Xiaoyao Tenglong on 2019-1-29 at 08:29. To connect this to DCS, an isolator or intermediate relay must be added. With so many 24V power supplies in the DCS, does it mean that the status of each one needs to be monitored? With DCS’s so-called loop power supply, it’s very difficult for the fuses to blow without anyone even realizing it. A DCS can handle the issue by setting an alarm; I don’t think it’s necessary to have special monitoring in place for safety reasons. For controlling the power supply to the circuits, we use main circuit breakers; fuses are installed for each circuit. It seems that fuses are not integrated into the DCS… If all these elements are incorporated into the DCS, then is there still a need for routine inspections? Inspect once a day, and take random samples of the terminals once a month. In any case, there have been no reports of control room fuses blowing due to normal operation on site.
The status of electrical components cannot be monitored; only the status of electrical equipment can be monitored.
It can be monitored by connecting a relay in parallel between the lower terminal of the fuse and other loads. Then select the normally open/normally closed contact of that relay as needed
The fuse itself does not have a status signal; if necessary, a relay can be connected, with the signal being taken from the relay’s auxiliary contacts
Thank you everyone for the discussions! Regarding the method of using relays in conjunction with fuses, there is already a concern that the fuses might fail; by adding another relay, an additional point of failure is created. In electrical control systems, it is common for fuses in the secondary circuits to burn out, which is why it is necessary to include monitoring for fuses as well. For implementing automatic control nowadays, a fault analysis function is required; therefore, it is necessary to monitor the operating status of each component in the electrical circuit.
An isolation barrier or relay is used for the output, thereby preventing short circuits from causing the fuses to fail; instead of feeding the fuse signal into the DCS, this isolation ensures that even if there is a short circuit in the field signals, it will not affect the entire system. From a holistic planning perspective, this approach ensures that short circuits only affect individual circuit signals.