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Content 4/4

This is an open hardware design for an electrical distribution panel and smart

marine platform (boat) controller.


You can think of this as a giant latching relay board with a socket to act like

a regular Raspberry Pi HAT or an Nvidia Jetson (Nano/Xavier NX) breakout


All critical parts are designed to be field serviceable, components using

through-holes are used where possible for better durability in mobile marine 

environments. Note that these boards need to carry significant amounts of current

(up to 660 Amperes!) and voltage (max 277V) and as such PCB thickness and

clearances are CRITICAL along with proper thermal management.


IMPORTANT - Note that RJ45 Inputs are not isolated or protected from ESD, if there is any

chance of surges or high voltages these should be isolated from the board using

digital isolators or optocouplers and transient voltage suppressors. For remote

installations of the Raspberry Pi/Jetson you might also want to add debounce and

and provide 3v from an isolated source.


Special care has been taken to limit power consumption wherever possible, on

it's own the board will only consume {INSERT_WATTS} watts when idle, if a

Raspberry Pi (Rpi) Zero is mated it will add 80mA, a fully fledged RPi 4

with all the bells and whistles will ad up to 3.4 Watts, a Jetson Xavier NX

will bring the total to 10-15 Watts depending on configuration. Jumpers are

provided where applicable to disable LEDs to reduce power consumption when idle.


Effort was taken to make the boards as reliable as possible and enable them to

be operated in emergencies and under failure conditions. All circuits can be

operated manually on the board as long as the board has a power source over 6v

and below 30v depending on configuration (see optional 12V vs 24V operation and

PSU). Operation using external 5V TTL inputs is available regardless of the

state or presence of the RPi/Jetson.


The board can be configured to run in either 12V or 24V mode, for operation

over 13V please make sure the optional 12V PSU option is in place and

configured. For 12V operation make sure the 12V bypass jumper/solder pads are

connected.


The design includes a main board and two optional addon boards, the primary

board is designed for 4 layer 2.4-3.2mm PCBs with the following layers:


  Front Power, 6oz (220um) copper, min spacing 0.500mm)

  First Signal, 1ox (35um) copper, min spacing 0.250mm)

  Second Signal, 1ox (35um) copper, min spacing 0.250mm)

  Back Power, 6oz (220um) copper, min spacing 0.500mm)


  The high current daughter board is designed for 4 layer 1/13oz (35/450um) copper.

  The non-latching daughter board is designed for 4 layer 1/6oz (35/200um) copper.

  The non-existent current sensing daughter board .. will probably use 6oz copper.

  The non-existent ESD optocoupler/isolator board .. will probably use 1oz copper.


  PCB Stack Thickness of daughter boards can very as long as they are over 1mm


It's important that the power layers are on the outside for cooling purposes,

internal layers would require substantially thicker copper layers.


There aren't very many PCB manufacturers around that will/can produce a board

like this, especially in small quantities and the tooling fee will be a

substantial part of the total cost.


At the time of this writing I would estimate at least $400 USD for the tooling

setup and then $350 USD for each board manufactured. The manufacturers that

have online order forms for 4 layer heavy copper PCBs are:


https://www.pcbcart.com

https://www.pcbway.com

https://pcbgogo.com


This layout includes:


16 x 0-24V DC Common input channels/circuits with the following:

  Input polarity protection and indicator LED

  Latching relay rated for 24V DC

  Thermally fused to 3A (can be swapped for 6A, 10A and 16A)

  Total current of these circuits should not exceed 60A


8 x 0-24V DC Common input channels/circuits with the following:

  Input polarity protection and indicator LED

  Latching relay rated for 24V DC

  4 x thermally fused to 6A (can be swapped for 6A, 10A and 16A)

  2 x thermally fused to 10A (can be swapped for 6A, 10A and 16A)

  2 x thermally fused to 16A (can be swapped for 6A, 10A and 16A)

  Total current of these circuits should not exceed 60A


8 x 100-250V AC Common input channels/circuits with the following:

  AC Live/Neutral indicator LED

  Latching relay rated for 24V DC

  4 x thermally fused to 6A (can be swapped for 6A, 10A and 16A)

  2 x thermally fused to 10A (can be swapped for 6A, 10A and 16A)

  2 x thermally fused to 16A (can be swapped for 6A, 10A and 16A)

  Total current of these circuits should not exceed 60A


Latching Relay Addon Board

8 x 0-277V AC/DC Individual input/output channels/circuits

  Individual channel current should not exceed 60A

  No circuit breakers, polarity indicators or protection


Non Latching Paired NO Addon Board

16 (8 pairs) x 12V DC non latching input/output channels/circuits

  Individual channel current should not exceed 32A

  No circuit breakers, polarity indicators or protection

  NOTE, relays are paired and only one of a pair can be powered

  at any given time.


Each channel/circuit can be controlled using three different methods:


  1. Using the onboard switches (these directly energise the relay coils)


  2. Using two external switch signals wired up using CAT5/6 with RJ45

    connectors. The signals use 5V TTL logic and are active HIGH.

    The signals are filtered for noise and duration to protect the relays,

    this ensures that only one coil can be energised at any given time and

    only for a period of 1 second. Due to this filtering these can be safely

    wired to 3-way "Latching" wall/panel switches or momentary push buttons.


  3. Using I2C via the 2x20 Header, typically this would be done using a

    Raspberri Pi (RPi) or Nvidia Jetson, for power efficiency consider using a RPi Zero.

    See Node-Red source for IoT web based interfaces that can run on these

    platforms.


Onboard bi-colour LEDs indicate coil energy state and pulses to "ON"/"OFF" coils.

For latching relays RED indicates the circuit being turned ON while GREEN indicates the circuit being turned OFF.

For non-latching relays RED and GREEN each represent a separate relay in a

pair.


Technically this can be considered to be a Raspberry (RPi) HAT which I believe would make

it the largest one in existence but the board does not require an RPi to

operate. Note that the board will act as a power supply for the RPi and Jetson

Nano and eliminates the need for a separate PSU to power the RPi/Nano.


All communication between the RPi and the board is done using I2C, this only

requires 2 wires and makes it safe to use in combination with most if not all

other hats. In particular it can co-exist with the Moitessier HATs though you

might want to run your chart-plotting or navigation software on a separate

RPi/Jetson NX and have a dedicated micro-computer for controlling your electrical system.


I2C interface and addresses

  Channels/Circuits are grouped up in banks of 8 for a total of 16 signals,

  ON/OFF for each relay. The I2C addresses can be modified using solder

  jumpers next to the IO Expanders but the defaults are:


  0x20 3A Common Input DC #1-8

  0x21 3A Common Input DC #9-16

  0x22 6/10/16A Common Input DC

  0x23 6/10/16A Common Input AC

  0x24 60A Individual AC/DC

  0x25 Additional IO #1 to RJ45 Cat5/6

  0x26 Additional IO #2 to RJ45 Cat5/6


Extra pins/IO on Cat5/6 via the RJ45 Connectors

  In addition to the 5V TTL active-low signals to control the relays there

  are a couple of additional IO ports and pins available via RJ45.


  All the RPI pins

  {INSERT_PINOUT_HERE}


  Two MCP23017 TTL outputs


For examples of how to use Node Red to control this board see

  {INSERT_NODE_RED_LINK_HERE}

  {INSERT_NODE_RED_DEMO_HERE}


Feel free to modify this to suit your own needs or have it made as it's

currently configured. Be careful when upgrading circuit breakers to not exceed the

current/thermal capacity of the board. If you use thinner copper than 6oz make

sure to appropriately downgrade the thermal breakers to reduce maximum current.


# Key features

* All critical components are through-hole for field maintenance on moving platforms and secure attachment for vibration and G loads.

* All relays can be controlled from either the RPi/Nvidia or using analog control signals via RJ45/CAT5/6 connectors/cables.

* All onboard relays are latching dual coil with individual control circuits.

* All analog input channels have pulse generators for the relays to protect them from overheating.

* Built-in high efficiency 5/12v step down converers to power the RPi/Nano and logic components and supply current for analog control.

* 8x 3-16A 250V AC shared bus protected circuits

* 24x 3-16A 12-24V DC shared bus protected circuits

* 32x 12-24V 500mA DC Logic/Relay breakout via RJ45

* Optional 16x 250V AC non-latching unprotected add-on board

* Optional 8x 60A 277V AC latching individual unprotected add-on board


* All onboard DC channels are polarity protected with high efficiency PFETs


Protection is provided using thermal circuit breakers, the permitted amperage can be changed by switching out breakers, no breakers are provided for the 60A circuits, suggest usin

Apr 11,2021
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