10.5
JPDE DC Battery Power Distribution
10.5.1
Functional Description
The dc Battery Power Distribution (IS410JPDE) board receives dc power from a battery or power supplies and distributes it
to terminal boards and other system loads. JPDE supports a floating dc bus that is centered on earth using resistors and
provides voltage feedback through PPDA to detect system ground faults. It provides inputs for two power supplies. JPDE is
able to operate at either 24 V dc or 48 V dc. JPDE integrates into the PDM system feedback offered through the PPDA I/O
pack.
This board is limited by the current that can be passed through it using conventional board construction. JPDE does not
supply power to bulk 500 W - 24 V input/28 V output power supplies providing I/O pack control power.
JPDE is the PDM element that receives dc power from a battery or power supplies and distributes it to I/O such as relay and
contact input boards. JPDE supports a floating battery bus that is centered on earth using resistors, and provides voltage
sensing to detect system ground faults. It provides inputs for two power supplies including their associated status contact
feedback. The design is compatible with applications using either 24 V or 48 V dc.
The current that can be passed through the board (using conventional board construction techniques) limits the amperage
capabilities of this board. For this reason, the JPDE is not intended to supply power to bulk 500 W 24 V input / 28 V output
power supplies providing I/O pack control power. Each one of these supplies will consume approximately 25 A at full load. A
set of three for R, S, and T would then use 75 A, exceeding the conventional capability of circuit boards. While special board
construction is possible to address the high current, the resulting high product cost would exceed the cost of using more
simple and readily available commercial components.
When power distribution is needed for I/O, it is more functional to have a board that provides centering resistors for a floating
bus, voltage feedback for magnitude and ground detection, status feedback from dc power supplies, and fused output
monitoring. The JPDE addresses these needs.
10.5.2
JPDE I/O Characteristics
•
For JPDE battery applications, four battery input screw terminals located adjacent to the board on a barrier terminal strip
are used. Nominal rating of the dc input path is 30 A, and the voltage is not expected to exceed 60 V. Protection of the
branch circuit (supplying power to this input) is expected to be no greater than a 30 A breaker. This is the primary power
input.
•
JD1 is a six pin Mate-N-Lok connector that accepts the power input from external dc power sources such as a battery
when a wire harness is to be used.Three connector pins are used for each side of the dc input to provide adequate current
rating.
•
Two power supply inputs are provided on JPS1 and JPS2. The connector uses pins 8 and 9 for positive 24 V or 48 V. Pins
1-3 are used for 24 return, providing 24 A steady state capacity. These connectors include low level signals capable of
detecting status switches on each supply and generating a feedback signal to PPDA. Pin 4 provides positive 10 V wetting
to the switch, and the return is on pin 5.
•
There are three fused, switched, four-pin Mate-N-Lok output connectors: JS1, JS2, and JS3. Positive power is on pins 1
and 2, negative power is on pins 3 and 4. This matches the pin use on JPDD J28 and J28X. Fuse rating is 7 A.
•
There are three fused four pin Mate-N-Lok output connectors JFA, JFB, and JFC. Positive power is on pins 1 and 2,
negative power is on pins 3 and 4. This matches the pin use on JPDD J28 and J28X. Fuse rating is 15 A.
•
Ground reference jumper JP1. The dc bus is normally operated without a hard ground connection. It is desirable to center
the dc on earth as part of the ground fault detection scheme. In normal 24 V operation, the dc positive terminal would
measure ½ * 24 V above ground, while the negative terminal would measure the same magnitude below ground potential.
The resistors to center the bus on earth may either be supplied external to the JPDE, or on-board resistors may be used by
closing jumper JP1.
•
Diagnostic daisy chain 50 pin ribbon cable connectors P1 and P2 on top and bottom of the board for pass-through of the
diagnostic signals are discussed in the next section.
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GEH-6855_Vol_II Mark VIeS Functional Safety Systems Volume II
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