Allen-Bradley 1771-HRA Resolver Excitation Module

The 1771-HRA is an Allen-Bradley Resolver Excitation Module designed for use with the IMC 120 motion control system. It generates sine and cosine excitation signals for the stator of an IMC 120 resolver and provides resolver position feedback to controller modules. Its documented features include a 2.5 kHz excitation output, analog command signals, and a dedicated power supply and cable arrangement.

Key Features

• Resolver excitation module for the IMC 120 system.
• Generates sine and cosine excitation signals for resolver feedback.
• Supports resolver-based position measurement.
• Provides a +/-10 VDC analog command output.
• 2.5 kHz sine and cosine excitation output frequency.
• Green LED power status indicator.
• Uses a dedicated 1771-PS7 power supply module.
• Compatible wiring arm identified as 1771-WA.

Technical Specifications

Resolver Excitation and Feedback Operation

The 1771-HRA generates the sine and cosine reference signals required to excite the stator of the IMC 120 resolver. The resolver responds to shaft position by producing corresponding feedback signals, which allow the motion control system to determine position.

The relationship between the sine and cosine signals is important for accurate resolver-based position measurement. The specified amplitude matching and signal distortion characteristics describe the quality of the excitation signals supplied to the resolver.

Power Supply and Connection Requirements

The module uses the 1771-PS7 power supply module, which provides 5 VDC, 15 VDC, and 24 VDC power. A 1771-CAS cable connects the power supply to the module's 12-pin Latch and Lock connector.

For field connections, the listed 1771-CAPR cable has a length of 12 ft and connects the module to the termination panel. The specified 1771-WA wiring arm should also be considered when checking the existing chassis wiring arrangement.

Resolver Signal Characteristics

The resolver excitation outputs operate at 2.5 kHz and provide matched sine and cosine reference signals. The specified RMS amplitude range is 6.72-7.42 V, with a maximum sine-to-cosine amplitude mismatch of 0.3%.

These quadrature signals provide the reference excitation needed by resolver feedback devices. The IMC 120 documentation describes support for up to six receiver-type resolvers, with two resolver connections available per 15-pin D-shell connector.

docs.rs-online.com+2

Power and Cabling

The 1771-PS7 supplies the module's user power through a 1771-CAS cable and a 12-pin latch-and-lock connector. The documented supply rails are +5 VDC, +15 VDC, -15 VDC, and +24 VDC, with common connections. The module also connects to the resolver termination panel through a 1771-CAPR cable.

Rockwell Automation+1

The green LED provides a visual indication of power status. When checking an existing installation, verify the power connections and resolver cable routing against the IMC 120 installation documentation.

Technical Parameters and Performance

The module's documented signal characteristics include a maximum offset voltage of 0.01 VDC and signal distortion of 0.1% THD. These values are relevant when checking resolver excitation quality and investigating position feedback discrepancies.

The module also incorporates current-limit protection on its resolver stator drive outputs. This protection helps limit output current under abnormal loading conditions, including certain resolver or wiring faults.

Computer Program+1

Frequently Asked Questions

Q: Which motion control system uses the 1771-HRA?

A: The 1771-HRA is designed for the Allen-Bradley IMC 120 motion control system. It provides resolver excitation signals for the system's position feedback devices.

Q: Which power supply is required for the 1771-HRA?

A: The specified power supply is the 1771-PS7. It distributes the required DC supply rails through 1771-CAS cables.

Q: How many resolvers can the excitation system support?

A: The IMC 120 documentation describes support for up to six receiver-type resolvers through three 15-pin D-shell connectors, with two resolver connections per connector.

Artisan Technology Group+1

Q: Which cable connects the module to the termination panel?

A: The 1771-CAPR cable is identified for this connection. Check the required cable length and termination arrangement against the installed system documentation.