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DB BOARDS and mixing DC control circuits and AC power MCBs - COMPLIANCE


CCC Telecom
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Anyone know the regulations on low power DC signal cables for relays in the main AC Inverter Isolation Board also used as Load Control:

Here we want to trigger AC transfer switches with a standard 230V/24V intermediate control relays

so the purpose of the load control board and main AC Isolation board is as follows: 

 

1) Isolators to Receive Power from Eskom Point of Control Isolator (Usually arriving from Main Load DB Board Top Left)

2) Circuit Breakers for each Inverter Input and Output and 1P Surge Protection Devices for every Live wire

3) Combine Battery Inverter and PV Inverter AC Outputs into common AC output

4) Use ATS to switch between Eskom and Inverter Output 1 or 2 = Bypass Switch (Entire System) instead of a lever handle in a box

5) Use 2nd, 3rd, 4th ATS  (Bypass switch per load group e.g. high power loads) here the ATS still switches between eskom and output1 but with 

different load DB board destination appliance groups (sub DB boards in the same load db board)

6) Present Several Exit Isolation MCBs for return trip to the Load DB Board with has on arrival isolators for the same

7) Meter everything as required in the main AC Isolation board

 

A.  Someone suggested I might need a separate DB Board for each ATS, that seems a bit far out and messy when they are using the same two power sources ? Inverter and Eskom

     The only difference is the target Load DB Board # in the Separate Load distribution Board

B. I now want to activate the ATS's using standard 24VAC/DC activation and 230V control relays (Intermediate Relay)

Lets look at a MultiPlus II with an Orion 48/24 DC-DC converter as power source for the NO/NC contacts (Blue relay terminals in multiplus) and activator source 24VDC for for the Intermediate relay which switches the ATS using the intermediate relay and ATS 230VAC control circuits

 You guessed that I now have very low current DC cables in the otherwise AC board to get the intermediate relay to activate the AC ATS, is this OK or have I got to use a separate dedicated micro DB board for the intermediate relays to avoid the DC control signal wires entering the Main AC Isolation / Load Control Board ?

C. Using SU boards (Metal, there is a Metal SU7 DB Board with 3 *24 DIN on one door and 3*15 DIN on the other door, can I use this and put DC in the one side and AC in the other side, it looks like 2 DB Boards and each side has a separate door and is isolated from the other side, or is this also going to have a problem with Compliance

I can simply buy 2 SU5 boards and put them next to each other, so I can't see that an SU7 DB Board is going to have a problem - or is it ?

Edited by CCC Telecom
change word voltage to current
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1 hour ago, CCC Telecom said:

You guessed that I now have very low current DC cables in the otherwise AC board to get the intermediate relay to activate the AC ATS, is this OK

Normally this is not a problem as long as you do not use the standard red, white, blue, black colors of 400VAC for the low voltage circuits, Rather use different colors like example orange, pink, grey, purple etc. for low voltages and fit wire numbers stating 24VDC. Where the low voltage wiring enter the 400VAC board, put the dc wires inside pvc slotted trunking to keep dc separate from ac and where dc wires exit the slotted trunking to the ATS wrap the exposed bits that connect onto ATS with those pvc coil wraps to protect it from damage or touching 400VAC. That should normally pass a inspection unless the company has their own higher standards. Hope it makes sense. 

 

1 hour ago, CCC Telecom said:

can I use this and put DC in the one side and AC in the other side, it looks like 2 DB Boards and each side has a separate door and is isolated from the other side, or is this also going to have a problem with Compliance

This should not be a problem as they are divided.

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16 hours ago, Gerrie said:

Normally this is not a problem as long as you do not use the standard red, white, blue, black colors of 400VAC for the low voltage circuits, Rather use different colors like example orange, pink, grey, purple etc. for low voltages and fit wire numbers stating 24VDC. Where the low voltage wiring enter the 400VAC board, put the dc wires inside pvc slotted trunking to keep dc separate from ac and where dc wires exit the slotted trunking to the ATS wrap the exposed bits that connect onto ATS with those pvc coil wraps to protect it from damage or touching 400VAC. That should normally pass a inspection unless the company has their own higher standards. Hope it makes sense. 

 

This should not be a problem as they are divided.

Thank You, that sounds like a great idea, 16mm slotted trunking takes up 1 DIN MOD since I have the Intermediate relays in the same position on each row it can go across all 3 rows of MCBs in the DB Board from top to bottom to deliver the DC control wires and then from the DC panel on the left hand side of the SU7.

 

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