Allen-Bradley Power Supply Module 1771-P4S
The 1771-P4S Power Supply Module is a 5V, 8A power supply that can be used in the 1771-A1B, -A2B, -A3B, and -A4B Universal I/O Chassis. Up to two of these supplies may be used as dictated by the power requirements of the 1771 series I/O modules contained in the Universal I/O Chassis. If two supplies are used, they must be connected by a Power Supply Paralleling Cable.
1771-P4S Power Supply Module Strapping
Place the module so that the right hand cover plate (the one with the labels) is facing down on a flat surface, and the front of the module is facing away from you. The module should appear as it does in figure 3.1 with the two configuration jumpers just behind the gold connecting traces of the circuit board. These jumpers select the proper voltage regulation for the different power supply configurations. The right position (rarely used in an EPICS control system) selects the configuration for a single power supply in a power supply chassis, connected to an I/O chassis through a power supply cable. In an EPICS control system, they should be configured as they appear in figure 3.1, with both of the jumpers located on the left hand side of the three pin headers.
1771-P4S Power Supply Module Installation
The Allen-Bradley 1771-P4S Power Supply Module may be installed in any Allen-Bradley Universal I/O Chassis, 1771-A1B, 1771-A2B, 1771-A3B, or 1771-A4B. Each module supplies a maximum of 8A to the other modules in the I/O crate. Two of these modules may be used per I/O chassis to supply a maximum of 16A to the other modules in the chassis. Adding the current requirements of all of the modules in the I/O chassis will indicate if two power supply modules are needed, or if one will suffice.
The Allen-Bradley 1771-P4S Power Supply Module itself requires 120V AC (actual voltage input range is 97 - 132 VAC rms) at a frequency of 47 - 63 Hz. The module is protected with a 1.5A 250V Slow-blow fuse located on the front panel.
Module Location in the I/O Chassis
The Allen-Bradley 1771-P4S Power Supply Module may be placed in any slot of the I/O chassis with the exception of of the extreme left slot. This slot is occupied by the Remote I/O Adapter Module. It is suggested that the power supply modules be placed away from analog input modules and low voltage DC modules to minimize electrical noise interference.
Before a power supply module is inserted into the Universal I/O Chassis, be sure that the power switch is in the off position, and that the 120VAC cable is disconnected from the module. If a Remote I/O Adapter is currently in the Universal I/O Chassis, this procedure can be done without shutting off the IOC that the Universal I/O Chassis is connected to, and without removing the subnet communication link. To insert the module, place it in the plastic tracks on the top and bottom of the Universal I/O Chassis. Slide the module into the Universal I/O Chassis until the module comes in contact with the backplane connector. Do not force the module in, instead apply firm and even pressure on the module to seat it properly on the backplane connector. Snap the chassis latch over the top of the module and connect the 120VAC connector to the module. The Universal I/O Chassis should begin communicating with the host IOC when the power is switched on, no rebooting of the IOC will have to be done.
Connection of the 120VAC power to the 1771-P4S is accomplished through the use of a Wago 231-205/000-008 connector (Allen-Bradley part number 941274-05) included with each 1771-P4S. figure 3.2 illustrates how the 120VAC power should be connected to the 1771-P4S modules. Note that two modules are illustrated in figure 3.2, only one power supply module may be needed depending upon the current requirements of the modules in the Universal I/O Chassis.
Using Two Power Supply Modules
If two power supply modules are used in one Universal I/O Chassis they must be linked together through the Power Supply Paralleling Cable, Allen-Bradley part number 1771-CT. This connection is a communication link between the two supplies. If one of the supplies has to shut down, it informs the second supply to turn off its P/S ACTIVE indicator. If this shut down procedure does occur, the Remote I/O Adapter will be disabled, however, the second supply will continue to supply power until its DC output limits are exceeded. Because the Remote I/O Adapter will be disabled if either of two power supply modules shut down, placing two power supplies in one Universal I/O Chassis does not provide redundancy. The Power Supply Paralleling Cable should be looped over the top of the I/O chassis to avoid picking up signals induced from the I/O wiring.
1771-P4S Power Supply Module Use
The 1771-P4S is used by simply turning on the power switch located on the front of the module. If two supplies are being used, turn them on simultaneously, otherwise the first supply powered on may shut down due to an over-current condition. Remember to shut the supply, or supplies down when inserting or removing any module from the Universal I/O Chassis.
The front of the 1771-P4S contains a P/S ACTIVE (power supply active) indicator. If the indicator is illuminated green, the power supply, and any supply connected to it through a power supply paralleling cable is operating normally. Note that this does not guarantee that the power supply is correctly inserted and supplying power to the backplane. If the indicator is off the power supply module has detected one of the following conditions: DC over-voltage, DC under-voltage, DC over-current, power switch turned off, AC under-voltage, or that any power supply module connected to it through a power supply paralleling cable has detected a similar condition.
