Products > AC-PRO-II


The AC-PRO-II® is 55% smaller than the original AC-PRO® and has the standard trip unit functions of Long-Time, Short-Time, Instantaneous and Ground Fault.

Click here for a list of breakers for which AC-PRO-II kits are available.

The AC-PRO-II® also includes the following additional features. AC-PRO-II, Trip Unit

  • Neutral Overload
  • Under-voltage alarm/trip*
  • Over-voltage alarm/trip*
  • Time stamping of events
  • Ground Fault Alarm
  • Test Mode
  • Communications
  • Patented Sluggish Breaker® detection
  • Wave form capture
  • Configurable alarm relay
  • Phase Loss/Reverse Phase Alarm/Trip*
    (Protects Against Single-Phasing)
*Requires VDM Option

Comparison of AC-PRO vs AC-PRO-II Features and Settings

Advantages of AC-PRO-II vs AC-PRO Video

UL and CE Certification

CE LabelTo ensure that the AC-PRO-II® will function when needed it was tested to the ANSI C.37.59 Standards for fault interruption. As a result of this testing the
AC-PRO-II® is UL listed on a variety of breakers. Please see the AC-PRO-II® UL Listings table for a compete breakdown.

The UL mark is in the process of being updated and modernized by UL. When Utility Relay Company designed the AC-PRO-II® we decided to use the new enhanced version of the UL mark so we would be compliance with any future UL regulations.

The SAFETY US-CA wording on the UL label designates that our product has been evaluated to United States and Canadian safety requirements. If you have more questions about this please visit the UL website for more details. UL-Marks for North America

The E number at the bottom of the mark is a unique identifier that can be used to access more information about the products UL certification. Utility Relay Company's official UL info can be found here: UL AC-PRO® Product Family

AC-PRO-II® UL Listings
Manufacturer Breaker Model Breaker Rating
Allis-Chalmers LA-1600 1600A
General Electric AKR-75 3200A
ITE K-3000 3000A
ITE K-600 600A
ITE K-800 800A
Westinghouse DS-206 800A
Westinghouse DS-416 1600A
Westinghouse DS-632 3200A
Westinghouse DB-50 1600A
General Electric Ak-2-50 1600A
General Electric Ak-2-75 3000A
ITE K-1600 1600A
ITE KB Steel Back 600A
Schneider Electric Series H-3 800-4000A

The AC-PRO-II® was tested & is certified to withstand radio frequency interference per the ANSI C37.90.2 Standard

Backwards Compatibility

The CTs, Actuators and wiring harness from the original AC-PRO® can be used with the AC-PRO-II®. This makes upgrading the trip unit very simple and fast.



RS485 Modbus RTU communications is standard on every AC-PRO-II®. The AC-PRO-II® can be integrated into various industry standard HMI systems that have a Modbus RTU driver. A few examples are:

•  Schneider Electric ION-Enterprise™ •  Schneider Electric SMS-3000™
•  Wonderware’ s INTOUCH™      •  Power Measurements PEGASYS™
•  Siemens WinPM™  

USB Port

The front mounted and electrically isolated USB port allows for easy downloading of trip data and protection settings using InfoPro-AC software. It can also be used to upload the trip unit settings, making commissioning the trip unit much faster.

USB Port is also intended for use with the SAFE-T-TRIP handheld trip device.

NOTE: If the AC-PRO-II® is located behind a cubicle door, a USB panel mount extension will be provided with the retrofit kit. Click here to see details on the USB panel mount extension.

A step-by-step installtion video of the USB mount extension can be found here.


Settings are programmed using the OLED multi-line display and smart buttons that change their function according to the information displayed. All of the settings are entered using simple parameters. No percentages or multipliers are required.

OLED Multi Line Display Unit

The easy to read multi-line display provides real time monitoring of 3-phase, neutral and ground fault currents. The display unit can be rotated to allow the trip unit to fit in a variety of different breaker configurations.

Last Trip Data

The trip units retains all of the trip data for that last 8 trip events. This data includes a date and time stamp of each event from the integrated real time clock. The waveforms are also captured for each of the 8 trip events.


The AC-PRO-II® is compatible with the QUICK-TRIP® Arc Flash Reduction system. The QUICK-TRIP® system is a manually controlled arc flash hazard reduction system. It can reduce trip times when turned on and allows selective coordination between circuit breakers when turned off.

If maintenance personnel must work on energized equipment, they will first turn the QUICK-TRIP® system on at the upstream breaker feeding the equipment or breaker. If a fault now occurs, the upstream breaker will trip quickly based on the QUICK-TRIP® settings reducing the Arc Flash Hazard to personnel. When the maintenance work is finished, the QUICK-TRIP® system is turned off and the original selective coordination is back in effect.


50Hz or 60Hz Operation

The AC-PRO-II® is user configurable for 50Hz or 60Hz applications.

"Self-Test OK" Feature

The green LED indicates that the trip unit is operating properly. The "Self-Test OK" feature performs the following:

  • Continuously monitors the trip unit
  • Verifies that the actuator is connected
  • Monitors the software routines
  • Monitors the micro-controller


  • Conformal coated circuit boards
  • Contamination resistant membrane
  • All metal nickel plated enclosure


All AC-PRO-II®’s come with a 2-year limited warranty.

Power Calculations

Whenever voltage and power data is necessary, a VDM (Voltage Divider Module) can be attached to the back of the AC-PRO-II® trip unit. With the VDM the following data is available on the display and through RS485 Modbus RTU communications.

  • Line-Line Voltages
  • KW
  • KVA
  • Power Factor
  • KWHr
  • KVAHr
  • Frequency


Graphical User Interface (InfoPro-AC)

A graphical User Interface application called the InfoPro-AC® is available for easy interface between a laptop computer and the USB port on the AC-PRO-II®. The InfoPro-AC® will provide access to the following items:

  • Trip unit settings
  • Current, Voltage & Power readings on demand
  • Waveforms on demand
  • Data on the last 8 trips including the waveforms.
  • AC-PRO-II® settings
  • Trip Data and protection parameters can be saved for later use
  • The protection parameters can also be uploaded using the InfoPro-AC

Sluggish Breaker® Detection

The patented Sluggish Breaker® operation detection captures the interruption time for a first trip. Later operations are faster because the breaker mechanism was exercised. If the mechanism operating time is excessive, the AC-PRO-II® will alarm that breaker maintenance is required.



The AC-PRO-II® is also compatible with Utility Relay Company's SAFE-T-TRIP® which provides a means for an operator to safely trip a breaker without having to stand directly in front of the switchgear.

ISO 9001

Product Information

Product Fliers

AC-PRO-II® Product Flier

AC-PRO® & AC-PRO-II® Test Set Product Flier

QUICK-TRIP®For AC-PRO-II® Product Flier

Instruction Manuals

AC-PRO-II® Instruction Manual

AC-PRO-II® Quick Start Manual

AC-PRO® & AC-PRO-II® B-292 Test Set Manual

AC-PRO & AC-PRO-II® LT Trip Times

MODBUS Communications

AC-PRO-II® Modbus Communications Register Map


InfoPro-AC®, AC-PRO-II® Software Application

Firmware Information

Firmware Versions

Firmware Release v2.0 Notes and FAQ


Rotating the Display on the AC-PRO-II®

Clearing Trip History on the AC-PRO-II®

Changing the Battery on the AC-PRO-II®

Reviewing Trip Data on the AC-PRO-II®

Installing the Quick Trip System

Installing the USB Extension Port