Mitsubishi Electric Q26UD(E)HCPU User Manual page 219

When a redundant power supply system is configured and one redundant power supply module has failed, the system is
operated using the other redundant power supply module only during replacement of the failed redundant power supply
module.
Therefore, keep the current consumption of the redundant power supply base unit (Q3
5VDC rated output current (8.5A) for one redundant power supply module.
(a) Cautions for using the extension base unit (Q5B)
When Q5B is used, a power of 5VDC is supplied from the redundant power supply module on the redundant
power main base unit (Q3RB) through an extension cable.
Pay attentions to the following to use Q5B.
• Keep the sum of the current consumption on Q3RB and Q5B not exceeding the 5VDC rated output
current for one redundant power supply module.
• Because 5VDC is supplied to Q5B through an extension cable, voltage drop occurs in the extension
cable.
Select an appropriate extension cable so that a voltage of 4.75VDC or more is supplied at the "IN"
connector of Q5B.
For details of the voltage drop, refer to Page 88, Section 4.3.4.
(b) Methods for reducing voltage drops
The following methods are effective to reduce voltage drops at the extension cables.
1) Changing the module mounting positions
Mount a module with large current consumption on the redundant power main base unit (Q3RB).
Mount small current consumption modules on the extension base unit (Q5B).
2) Using short extension cables
The shorter the extension cable is, the smaller the resistance and voltage drops are.
Use the shortest possible extension cables.
(4) When the base unit is QA1S6
AnS series power supply
module (A1S61PN,
A1S62PN, or A1S63P)
Select the power supply module also in consideration of the current consumption of the peripheral devices
connected to the special function module.
For example, when the AD75TU is connected to the AD75P1-S3, the current consumption of the AD75TU must
also be taken into account.
B:

Base unit (QA1S65B or
QA1S68B)
I/O module (such as
AX10 and AY10)
Special function module
(such as AD61 and
AD75P1-S3)
CHAPTER 7 POWER SUPPLY MODULE
  
RB/Q6 RB/Q6 WRB) within the
Peripheral
(AD75TU)
7
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