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I have an existing distributed control system, which sends commands over long(ish) distances (via fibre optic cables) and controls low voltage switchgear. The control is generally manual - someone in the central control room selects an operation on-screen, and the low voltage switchgear several kilometres away opens or closes as commanded.
Recently the output module failed in an unusual way. Rather than the volt-free output contacts failing closed or open, the module started to pulse the outputs at approximately 3Hz. As this happened in the middle of the night, and communications to the module also failed, there was no way of knowing what was happening at the remote end. In fact, the circuit breakers were being opened and closed frequently, causing many problems. I'd like to make sure that this does not happen again. The manufacturer is carrying out a detailed failure analysis, but assures me that this mode of failure is previously unknown to him.
I'm looking for some kind of relay which will monitor the 'circuit breaker close' command. If this command is issued more than, x times in, y minutes, further close commands will be inhibited.
Does anyone know of a product that has this inherent facility? I'm keen to avoid programmable devices, as they may fail in the same mode.
Any help will be gratefully received.
Recently the output module failed in an unusual way. Rather than the volt-free output contacts failing closed or open, the module started to pulse the outputs at approximately 3Hz. As this happened in the middle of the night, and communications to the module also failed, there was no way of knowing what was happening at the remote end. In fact, the circuit breakers were being opened and closed frequently, causing many problems. I'd like to make sure that this does not happen again. The manufacturer is carrying out a detailed failure analysis, but assures me that this mode of failure is previously unknown to him.
I'm looking for some kind of relay which will monitor the 'circuit breaker close' command. If this command is issued more than, x times in, y minutes, further close commands will be inhibited.
Does anyone know of a product that has this inherent facility? I'm keen to avoid programmable devices, as they may fail in the same mode.
Any help will be gratefully received.
