2/12/2024 8:30 AM | |
Joined: 3/30/2020 Last visit: 10/5/2024 Posts: 4822 Rating: (987)
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May we assume the contactors are with 24V coils? The choice of relay vs transistor output is depending on what load you have, the needed switching current and the switching rate (how regular). The harder the output works, the less the life span of the output becomes. So the specification of the load needs to be evaluated vs what the output delivers. An inductive load is especially menacing. Even the expected switching live time specification for relay outputs differ depending on the load type. (Switching with inductive load is half that of resistive load. See the S7-1200 System Manual.) With that in mind, one may consider having an external relay before the contactor. The external relay is easier to service. Included with this response is an extract of recommendations of how to handle inductive loads (like contactors). The extract comes from the S7-1200 System Manual that is available from this support site. Attachmentextract.pdf (266 Downloads) |
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