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CPU 1212 AC/DC/Rly - power cable for relay outputs

Created by: Milosh at: 8/16/2012 2:48 PM (10 Replies)

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8/16/2012 2:48 PM	Rate (0)
Milosh Silver Member Joined: 8/16/2010 Last visit: 9/25/2024 Posts: 637 Rating: (12)	Hi all. On relay output connectors, CPU have 1L and 2L tags. In manual says that voltage range is 5 to 30 VDC or 5 to 250 VAC? iIs that mean that I can connect here +24VDC or 220VAC to power outputs?

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8/16/2012 3:00 PM	Rate (0)
0_Einstein Diamond Expert Joined: 7/7/2010 Last visit: 10/4/2024 Posts: 15264 Rating: (2422)	Milosh Hi all. On relay output connectors, CPU have 1L and 2L tags. In manual says that voltage range is 5 to 30 VDC or 5 to 250 VAC? iIs that mean that I can connect here +24VDC or 220VAC to power outputs? Yes, your relay controlled outputs can handle quite a range of AC & DC loads, but the current has a relatively low limit, and the total of all outputs also has a limit. Be careful to read the specification details in the manual to keep from overloading the total as well as each individual output. I have many running applications with 5VDC, 12VDC, 24VDC, and 120VAC on the same PLC's relay outputs (multiple add-on output modules). It really helps to have such flexibility and not have to worry about sinking or sourcing plc outputs.
	science guy
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8/16/2012 3:07 PM	Rate (0)
Milosh Silver Member Joined: 8/16/2010 Last visit: 9/25/2024 Posts: 637 Rating: (12)	First thanks. So I can connect relay outputs as on attachement? Attachment EPLAN.pdf (480 Downloads)

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8/16/2012 3:26 PM	Rate (0)
0_Einstein Diamond Expert Joined: 7/7/2010 Last visit: 10/4/2024 Posts: 15264 Rating: (2422)	Milosh First thanks. So I can connect relay outputs as on attachement? I use AutoCAD Electrical, not EPLAN, so I cannot tell exactly what the document is intended to say. If it shows the PLC relay outputs controlling 24VDC relays by applying 24VDC to A1 coil power terminal, then yes. I do this very often to control loads > 2A or high inrush loads with > 1A steady state current draw. We had one fairly large contactor with steady state current of just under 2A. The inrush actually crowbared a lower quality 10A power supply causing the contactor to chatter until the power supply fuse blew or the contactor managed to close. After a few of these attempts, we replaced the power supply with a higher overload capacity, and just to be safe, replaced the plc relay output module. We then put another relay between to control the contactor. Just be aware of the limitations and exercise due diligence. As an FYI, my involvement was to explain the plc output module limitations while options were being investigated to solve the problem for that large contactor's in-rush problem. I suggested the intermediate control relay and larger power supply, though a better quality power supply worked just fine.
	science guy
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8/16/2012 4:36 PM	Rate (0)
Milosh Silver Member Joined: 8/16/2010 Last visit: 9/25/2024 Posts: 637 Rating: (12)	One more notice. So, I can connect +24VDC to 1L and 2L pins of PLC??? If yes ouput voltage when PLC output is turned on is +24VDC. In your first answer, I can connect 220V AC to 1L and 2L. and wire directly to contactor A1 (or A2)?

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8/16/2012 4:49 PM	Rate (0)
0_Einstein Diamond Expert Joined: 7/7/2010 Last visit: 10/4/2024 Posts: 15264 Rating: (2422)	Milosh One more notice. So, I can connect +24VDC to 1L and 2L pins of PLC??? If yes ouput voltage when PLC output is turned on is +24VDC. In your first answer, I can connect 220V AC to 1L and 2L. and wire directly to contactor A1 (or A2)? If you connect both 24VDC and 220VAC to 1L & 2L, something bad will happen. You can connect 24VDC to 1L and 220VAC to 2L and then control both 24VDC & 220VAC loads. Keep in mind, there are example wiring diagrams in the system manual and if I remember right, also in the s7-1200 easy book. They are good points to review before wiring since the terminal configurations and layout can be confusing.
	science guy
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8/16/2012 5:07 PM	Rate (0)
Milosh Silver Member Joined: 8/16/2010 Last visit: 9/25/2024 Posts: 637 Rating: (12)	huggy_d1 You can connect 24VDC to 1L and 220VAC to 2L and then control both 24VDC & 220VAC loads. Ok...this is what I want to know. :)

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3/2/2016 2:26 PM	Rate (0)
Min_Moderator Platinum Member Joined: 9/3/2014 Last visit: 3/13/2019 Posts: 4767 Rating: (123)	New question published by lezard is split to a separate thread with the subject 24VDC power connection. Best regards Min_Moderator

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6/11/2019 6:31 PM	Rate (0)
RAmeeti Posts: 25 Rating: (0)	The question being asked here ties in directly with my long sought question as to the meaning of schematic symbol on the attached figure for the 1L & 2L contacts. I could not find this symbol of a Circle containing a Straight Line over an Alternating Line in any internet search with a lot of time spent. But alas, that symbol must be trying to tell us that it can be AC or DC. Is this symbol made up for this situation? Or was my search just not as thorough as I thought it was? Attachment AC.DC.Schematic.Symbol.png (218 Downloads)
RAmeeti Posts: 25 Rating: (0)	Last edited by: RAmeeti at: 06/11/2019 18:31:48
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6/11/2019 6:40 PM	Rate (1)
Hati Platinum Member Joined: 9/21/2012 Last visit: 10/4/2024 Posts: 4172 Rating: (464)	RAmeeti The question being asked here ties in directly with my long sought question as to the meaning of schematic symbol on the attached figure for the 1L & 2L contacts. I could not find this symbol of a Circle containing a Straight Line over an Alternating Line in any internet search with a lot of time spent. But alas, that symbol must be trying to tell us that it can be AC or DC. Is this symbol made up for this situation? Or was my search just not as thorough as I thought it was? It's a representation of the choice to use AC (up to 240VAC) or DC to supply the internal relay contacts of the PLC. If you read the manual further, you should find more diagrams and examples.

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This contribution was helpful to 1 thankful Users 0_Einstein

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