When Your POINT I/O Rack Runs Out of Backplane Power
A system integrator recently expanded a packaging line with six additional POINT I/O modules. The adapter’s backplane current budget was already maxed out. Adding modules caused intermittent dropouts on the new channels. The fix was not a bigger adapter. It was inserting an Allen-Bradley 1734-EP24DC expansion power supply mid-rack. This module injects fresh POINTBus current and creates a new field power segment, restoring stable operation without replacing the adapter or rewiring the cabinet.
What the 1734-EP24DC Actually Does
The 1734-EP24DC is a POINT I/O expansion power supply from Allen-Bradley. It passes 24VDC field power to I/O modules on its right side and extends backplane bus power to as many as 17 modules, depending on their current draw. It also isolates field power for modules to its left, creating a clean power partition inside the rack. A dark gray housing makes it easy to spot during inspection. Two status indicators — field power and 5V system power — give technicians immediate visual feedback.
Key Specifications That Drive Performance
Input Voltage and POINTBus Output
The module accepts 24VDC nominal input with a working range of 10–28.8VDC. POINTBus output current depends on mounting orientation. Horizontal mounting delivers 1 A at 10–19.2V input and 1.3 A at 19.2–28.8V input. Vertical mounting delivers 1 A across the full 10–28.8V input range. This matters in dense cabinets where orientation is dictated by panel layout.
Power Consumption and Thermal Load
Maximum power consumption is 9.8 W at 28.8VDC. Power dissipation is 3.0 W at 28.8VDC, and thermal dissipation is 10.0 BTU/hr at 28.8VDC. These figures help panel builders size enclosure cooling correctly.
Protection and Ride-Through
Reverse polarity overvoltage protection guards against wiring errors. When input voltage drops out for 10 ms at 10V maximum load, the output voltage stays within specification. That ride-through covers brief supply dips common on industrial power feeds.
Where This Module Earns Its Place
Packaging and Material Handling
Conveyor zones with many discrete I/O points benefit from a mid-rack power boost. The 1734-EP24DC keeps new modules powered without a full adapter upgrade.
Process Skids with Tight Cabinets
Vertical mounting allows installation in narrow enclosures. The 1 A vertical output rating supports moderate module counts in space-constrained skids.
Legacy POINT I/O Upgrades
When replacing older expansion supplies during a retrofit, matching the 1734-EP24DC’s current profile avoids overloading the existing adapter. This is a direct replacement path for systems already using 1734 POINT I/O adapters.
Installation and Setup Notes
Mount the module horizontally or vertically to match the POINT I/O system orientation. Insert it between the adapter and the modules that need additional POINTBus current. Verify that total module count on the right side does not exceed 17, and confirm the combined current draw stays within the output rating for your mounting orientation. Use the field power and 5V system indicators to confirm proper operation after power-up. Always follow the manufacturer’s installation manual for wiring and torque specifications.
Maintenance and Long-Term Reliability
The 1734-EP24DC has no moving parts, so wear is minimal. Operating temperature ranges from -13 to 140 °F, and nonoperating temperature ranges from -40 to 185 °F, at 5–95% relative humidity without condensation. Operating vibration is 5g at 10–500 Hz. Operating shock is 30g, and nonoperating shock is 50g. Inspect status indicators periodically and check for loose connections during scheduled maintenance. Keep the enclosure within the specified humidity range to prevent condensation.
Compatibility and Integration
The 1734-EP24DC works with any 1734 POINT I/O adapter. It integrates directly into existing POINT I/O racks without special firmware or configuration tools. The module’s isolation voltage is 50V continuous, which separates field power segments cleanly. Inrush current is 6 A for 10 ms, and power supply current is 10 A.
What to Verify Before You Buy
Confirm your adapter model and the number of modules you plan to add. Check whether your cabinet allows horizontal or vertical mounting, because output current differs. Verify that your 24VDC supply can deliver the inrush current without nuisance tripping. SpareTechPLC stocks genuine Allen-Bradley POINT I/O components and can help you match the right expansion supply to your rack configuration.
Frequently Asked Questions
How many modules can the 1734-EP24DC support?
It supports four to seventeen POINT I/O modules, depending on the current rating of each installed module.
Does mounting orientation change the output current?
Yes. Horizontal mounting provides 1 A at 10–19.2V input and 1.3 A at 19.2–28.8V input. Vertical mounting provides 1 A across the full 10–28.8V input range.
What happens during a brief input voltage drop?
The output voltage stays within specification when input supply voltage drops out for 10 ms at 10V maximum load.
Is reverse polarity protection built in?
Yes. The module includes reverse polarity overvoltage protection as an integral feature.
Which adapters are compatible?
The 1734-EP24DC is compatible with any 1734 POINT I/O adapter.
