Seeking help with issues related to safety barriers
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Dear masters on the forum, I’ve encountered a problem recently. It’s a three-wire audio-visual gas alarm; it works well when connected directly to the central control DCS – the on-site indicator lights and display screen come on, and alarm signaling is transmitted properly as well. Using a multimeter, 24V is detected at the power terminals of the instrument. However, if the transmitter is first connected to a safety barrier, the alarm device stops working. Only the indicator light will turn on; the display screen will not light up, there will be no alarm at the site, and no signal will be transmitted ； Using a multimeter, it was measured that the voltage at the power terminal of the instrument is only 5V, while the voltage supplied to the safety gate is 24V; this has been confirmed to be correct, and the wiring connections are also proper. I really can’t figure out what’s wrong...
The wiring methods for safety barriers in two-wire and three-wire systems are different; please check it
We have confirmed that the wiring is fine
The three-wire type is a passive signal; the instrument will not function without an power supply.
The safety barrier is connected to intrinsically safe instruments; is your three-wire gas detector intrinsically safe? It cannot operate properly if it is not intrinsically safe.
This is a power supply issue; just looking at the wiring diagram isn’t enough. In the situation you described, the wiring needs to be redesigned.
Does a combustible gas detector with audio, optical, and electrical alarms need a safety barrier?
The other two-wire instruments are also passive and can be used; moreover, the safety barrier can provide 24VDC power. I can’t quite figure out what the reason is
Could you tell me how to do it? The instruments on site have three terminal connections: V for power supply, S for signal, and G for the common terminal... The safety barrier also only has terminals designed for connecting three-wire transmitters
Is the acoustic and optical gas alarm an intrinsically safe instrument? Is the safety barrier explosion-proof through limitation, or is it because the power output of the safety barrier is insufficient?
Is it possible to wire it in this way: a 24V power supply is provided for the V and G terminals, while the S terminal and the G terminal are connected to the safety gate (it depends on whether the outputs from S and G are charged to determine whether an active or passive connection should be used for the safety gate; passive signals should be outputted). The signals from the safety gate are then fed into the passive channels of the DCS. I’m also very interested in seeing the wiring method for the three-wire safety gate you mentioned; I don’t have such a safety gate here