1756-PA72 85-265V AC Chassis Power Supply 75W 10A at 5.1V

The 1756-PA72 is a standard AC chassis power supply designed to provide regulated DC power directly to a compatible 1756 backplane.

It accepts a wide 85 to 265 V AC input range, allowing use with common 120 V and 240 V industrial control supplies. The unit converts the incoming AC power into the multiple DC voltage levels required by the controller, communication and I/O modules installed in the chassis.

The main difference of the 1756-PA72 is its 75 W total backplane power capacity combined with a 10 A output rating at 5.1 V DC. It is intended for standard chassis configurations where the calculated module load remains within these limits.

This is a non-redundant power supply. It should not be selected for systems requiring dual-power-source redundancy or uninterrupted switchover between two chassis supplies.

Key Features

• 85–265 V AC wide input range
• 47–63 Hz input frequency
• 75 W maximum backplane output
• 10 A output at 5.1 V DC
• Multiple regulated backplane voltages
• 250 V input-to-backplane isolation
• Standard chassis-side installation
• Non-redundant configuration

Typical Applications

• Controller chassis power
• Local I/O chassis assemblies
• Remote Ethernet I/O chassis
• Existing machine-control systems
• Standard non-redundant control panels

Wide-Range AC Input

The 1756-PA72 supports an AC input range of:

85 to 265 V AC

Nominal supplies include:

120 V AC

240 V AC

This wide input range simplifies replacement in control panels using different regional AC supply voltages.

The incoming supply must still meet the required frequency, grounding and overcurrent-protection specifications.

Backplane Power Function

The power supply provides regulated power directly to the chassis backplane.

Backplane outputs include:

5.1 V DC

10 A

3.3 V DC

4 A

1.2 V DC

1.5 A

24 V DC

2.8 A

These outputs power the modules installed in the chassis.

They are not intended to be used as general field-power terminals for external sensors, relays or actuators.

75W Total Output Limit

The combined backplane load must not exceed:

75 W Maximum

The total includes the power consumed from all backplane voltage rails.

A chassis can exceed the power-supply limit even when no single voltage rail exceeds its individual current rating.

The complete module list must therefore be checked with a chassis power calculation.

10A at 5.1V DC

The 5.1 V DC rail provides up to 10 A.

This rail is commonly used by:

• Controllers
• Communication modules
• Digital I/O modules
• Analog I/O modules
• Specialty chassis modules

The 10 A value is an individual rail limit and does not override the 75 W total-output limit.

Non-Redundant Configuration

The 1756-PA72 is a standard non-redundant chassis power supply.

It does not provide:

• Dual-supply operation
• Automatic supply switchover
• Redundant power monitoring
• External redundant power cabling

Applications requiring power redundancy should use the appropriate redundant power-supply architecture and chassis adapter components.

1756-PA72 vs 1756-PA75

1756-PA72

85–265 V AC input

75 W maximum output

10 A at 5.1 V DC

1756-PA75

85–265 V AC input

75 W maximum output

13 A at 5.1 V DC

The PA75 provides greater 5.1 V current capacity and is better suited to chassis configurations with a heavier module load.

1756-PA72 vs 1756-PB72

1756-PA72

AC input

85–265 V AC

120 / 240 V nominal

1756-PB72

DC input

24 V DC nominal

18–32 V DC operating range

Their backplane capacities are similar, but their input-power requirements are different.

1756-PA72 vs 1756-PA72K

1756-PA72

Standard environmental construction

1756-PA72K

Conformal-coated construction

Additional protection for compatible harsh-environment systems

The K version should be selected when the complete installation requires conformal-coated components.

1756-PA72 vs Redundant Power Supply

1756-PA72

Standard chassis-mounted supply

Single power source

No redundant switchover

Redundant Supply System

External redundant supply arrangement

Requires compatible chassis adapter and cables

Designed for improved power availability

A standard PA72 cannot be converted into a redundant system simply by installing a second standard supply.

Chassis Compatibility

The power supply must be matched to the chassis series.

Before replacement, verify:

• Chassis catalog number
• Chassis hardware series
• Existing power-supply series
• Installed module power demand
• Available panel clearance
• Input voltage
• Grounding arrangement

A physically similar supply may not be compatible with every chassis generation.

Power Load Calculation

Before installation, list every module in the chassis and calculate its demand on:

• 5.1 V DC
• 3.3 V DC
• 1.2 V DC
• 24 V DC
• Total output power

The calculation must remain below both:

• Each voltage-rail current limit
• The 75 W combined output limit

A higher-capacity supply may be required if either limit is exceeded.

Input Circuit Requirements

The AC input circuit should include:

• Suitable branch-circuit protection
• Protective grounding
• Correct conductor sizing
• Proper terminal torque
• Separation from signal wiring
• Compliance with local electrical codes

The power supply does not replace upstream circuit protection.

Open-Style Construction

The 1756-PA72 is an open-style industrial component.

It must be installed:

• Inside a suitable electrical enclosure
• In the correct chassis position
• Away from conductive contamination
• With adequate ventilation
• Within the specified operating temperature range

It is not a standalone enclosed AC/DC power supply.

Replacement Compatibility

Before replacing an existing supply, record:

• Complete model number
• Hardware series
• Chassis model and series
• AC input voltage
• Installed module list
• Calculated backplane load
• Grounding arrangement
• Existing alarm condition
• Terminal wiring

Replacing the supply without checking the chassis load can lead to overload or intermittent shutdown.

Installation Notes

• Place the controlled equipment in a safe state
• Disconnect and verify removal of AC power
• Record all existing input wiring
• Confirm chassis and supply compatibility
• Install the supply at the chassis left side
• Connect protective earth first
• Connect the AC input conductors
• Tighten terminals to the specified torque
• Confirm the chassis power calculation
• Apply power and check the status indicator
• Verify all chassis modules start correctly
• Test controller and I/O operation before production

FAQ

Q1: What input voltage does 1756-PA72 accept?

A1: It accepts 85 to 265 V AC at 47 to 63 Hz.

Q2: What is the maximum backplane output power?

A2: The maximum combined output is 75 W.

Q3: How much current is available at 5.1 V DC?

A3: It provides up to 10 A at 5.1 V DC.

Q4: Can it directly power 24 V field devices?

A4: No. Its outputs supply the chassis backplane and are not general-purpose field-power terminals.

Q5: Does it support redundant operation?

A5: No. It is a standard non-redundant power supply.

Q6: What is the difference from 1756-PA75?

A6: PA72 provides 10 A at 5.1 V, while PA75 provides 13 A at 5.1 V.

Q7: What is the difference from 1756-PB72?

A7: PA72 uses AC input, while PB72 uses a 24 V DC input supply.

Q8: Is a power-load calculation required?

A8: Yes. The installed module load must remain within every voltage-rail limit and the 75 W total capacity.