Utility Relay Company AC-PRO User manual

URC
Utility Relay Company
ac-pro®
i-ac-pro-QT ac trip unit
instruction manual
State of the art technology for low
voltage circuit breaker retrofitting
Chagrin Falls, OH 44023
Phone: [phone]
www.utilityrelay.com

AC-PRO®With QUICK-TRIP®Instruction Manual www.utilityrelay.com
Manual Rev 1.3
Section: Page
1.0 Introduction............................................................1
2.0 UL/ULC Classification............................................1
3.0 Trip Unit Power......................................................1
3.1 Current Transformer (CT) Power...................1
3.2 Battery Power................................................1
3.3 PT Module Power..........................................2
3.4 Auxiliary Power..............................................2
4.0 External Connections.............................................2
4.1 Breaker Wiring Harness.................................2
4.2 Security Key...................................................2
5.0 AC-PRO®Front View.............................................3
5.1 16 Character Display.....................................4
5.2 Pick-Up LED..................................................4
5.3 Self Test LED.................................................4
5.4 Display Contrast ............................................4
5.5 UP Push Button.............................................4
5.6 DOWN Push Button.......................................4
5.7 SAVE Push Button.........................................4
5.8 REVIEW Push Button....................................4
6.0 QUICK-TRIP®System ...........................................5
6.1 QUICK-TRIP®Basics.....................................5
6.2 QUICK-TRIP®Installation..............................6
6.3 QUICK-TRIP®& Pro-Display Operation.........7
7.0 Commissioning the AC-PRO®................................7
7.1 Powering-Up the Trip Unit .............................7
7.1.1 Internal Battery ....................................7
7.1.2 External Power ....................................7
7.2 Security Key...................................................7
7.3 CT Rating.......................................................8
7.4 Long Time (LT) Pick-Up Setting ....................8
7.5 Long Time (LT) Delay Setting........................8
7.6 Short Time (ST) Pick-Up Setting ...................8
7.7 Short-Time (ST) Delay Setting.......................8
7.8 Short Time (ST) I2T........................................8
7.9 Instantaneous (I) Pick-Up Setting..................9
7.10 Ground Fault (GF) Pick-Up Setting................9
7.11 Ground Fault (GF) Delay Setting...................9
7.12 Ground Fault (GF) I2T....................................9
7.13 Phase Unbalance (U/B) Pick-Up ...................9
7.14 Phase Unbalance (U/B) Delay.......................10
7.15 Address..........................................................10
7.16 Reply Delay ...................................................10
7.17 QUICK-TRIP®Ground Fault (QT GF)............10
7.18 QUICK-TRIP®Instantaneous (QT I) ..............10
7.19 Thermal Memory............................................11
7.20 Exit Procedure ...............................................11
8.0 Changing Settings..................................................12
9.0 Last Trip Data Recall .............................................13
10.0 Normal Operation...................................................14
11.0 Testing...................................................................14
11.1 Commission the Trip Unit ..............................14
11.2 LT Trip Test ...................................................14
11.3 ST Trip Test...................................................15
11.4 I Trip Test.......................................................15
11.5 GF Trip Test...................................................15
11.6 QT GF Trip Test.............................................15
11.7 CT Phasing Test for GF.................................15
11.8 QT I Trip Test.................................................16
11.9 U/B Trip Test..................................................16
11.10 Erase Last Trip Data....................................16
12.0 Secondary Injection Testing..................................17
12.1 AC-PRO®Secondary Injection Test Set........17
12.2 Standard Relay Test Set...............................17
12.3 LT Delay Testing Chart .................................18
13.0 Ratings..................................................................19
14.0 Warranty................................................................19
15.0 Time-Current Curves.............................................19
15.1 LT Trip Time..................................................20
15.2 ST Trip Time..................................................20
15.3 GF Trip Time.................................................21
15.4 U/B Trip Time................................................21
16.0 Error Message Summary ......................................21
16.1 Actuator Not Connected................................21
16.2 Memory Error ................................................21
17.0 Battery Replacement.............................................22
Figure: Page
4.1 AC-PRO®Top View...............................................2
4.2 Push Button “Key”.................................................2
5.1 AC-PRO®Horizontal Front View ...........................3
5.2 AC-PRO®Vertical Left Front View.........................3
6.1 QUICK-TRIP®Connections...................................5
6.2 QUICK-TRIP®Drilling Plan....................................6
6.3 Pro-Display Mounting............................................6
11.1 Phase A & B, CT Phasing Test.............................15
11.2 Phase B & C, CT Phasing Test.............................15
11.3 U/B Test ................................................................16
12.1 AC-PRO®Secondary Injection Test Set................17
17.1 Battery Replacement.............................................22
18.1 Typical Wiring Diagram.........................................23
18.2 Overload TCC .......................................................25
18.3 U/B & GF TCC.......................................................27
18.4 QUICK-TRIP®GF & I TCC....................................29
Firmware Revision: 5.26

AC-PRO®With QUICK-TRIP®Instruction Manual www.utilityrelay.com
Page 1
The AC-PRO is a state of the art, micro-controller based trip
unit for use on three phase, 600 Volt class, AC circuit
breakers. Models are available for use on 60 Hz, 50 Hz,
40 Hz, and 25 Hz systems.
The AC-PRO is a digital trip unit that uses a micro-controller
and a 16-character liquid crystal display (LCD).
The trip unit provides over-current, as well as short time and
instantaneous fault protection. All of the phase protection
functions use the true RMS currents including the
instantaneous trip function.
The AC-PRO measures the true RMS current through each
of the breaker’s three poles. For ground fault current, the
trip unit also does a vector sum of the three phase currents
(and neutral current if applicable) and determines the
fundamental frequency component.
The trip unit also offers ground fault and phase unbalance (U/B)
tripping functions as user selectable options. The fundamental
value of the ground fault current is used for the ground
fault trip function to eliminate nuisance ground fault trips
due to multiples of the 3rd harmonic.
The AC-PRO also has two additional QUICK-TRIP protective
settings that are intended to minimize Arc Flash Hazard. The
QUICK-TRIP ground fault and instantaneous trip functions are
turned ON or OFF using the QUICK-TRIP Display. See Section
6.0 for complete details.
The trip unit stores the last trip data and the trip log data in a
non-volatile FRAM memory for later recall. All the settings
are stored in non-volatile EEPROM memory. Battery backup
is not required.
The trip unit does not require external power to operate. Power
is derived from the current transformers (CTs). An internal
battery provides power to review and change protection
settings when CT power is unavailable.
All settings are made directly in amps or in seconds. A
security system reduces the risk of unauthorized tampering
with the trip unit settings.
The AC-PRO trip unit is manufactured under one or more of
the following patents:
US 7,646,575
US 7,889,472
Other patents may be pending.
AC-PRO is UL and ULC classified for use on the following
low voltage AC power circuit breakers:
Westinghouse DB-50
General Electric AK-50
General Electric AK-75
ITE KB Steel Back
FPE H-3
UL and ULC classification is in accordance with UL1066,
CSA C22.2, IEEE C37.59-1991 as well as appropriate
sections of ANSI C37.17-1979 and C37.50-1989.
AC-PRO was tested by an independent laboratory and found
in compliance with the following tests:
IEEE C37.90.2-2004, RF Susceptibility
IEEE C37.90.1-2002, Surge Withstand
15KV Electro-Static Discharge
Accuracy @ -20°C & +65°C
The AC-PRO can be powered in 4 different ways: CTs,
internal battery, PT module, or auxiliary power pack.
The AC-PRO derives both signal and power from the
breaker phase CTs. The trip unit will power-up with less
than 10% of the rated CT tap current through a single CT
(20% for the 1/2 Amp version). This current is below the
lowest pick-up setting.
A 9-volt, 750 mAh, long life, lithium battery is used in the trip
unit. This battery has less than 2 grams of lithium. There are
no restrictions on transport and no special methods of
disposal required with this battery.
The battery is designed to provide two functions:
1) Allow the user to commission (program) the trip unit
without using the auxiliary power pack.
2) Allow the user to recall the last trip data even if the
breaker is open and without using the auxiliary power
pack.
Press the “REVIEW” push button to turn the trip unit on
under battery power.
When on battery power, the trip unit will automatically turn
off 30 seconds after the last button is pushed to conserve
battery energy.
**** NOTE ****
The battery is NOT involved in the protective functions of
the trip unit. The trip unit will provide protection even if the
battery is removed.
The battery is NOT required for the trip unit to maintain
any of its memory including the user programmed pick-up
and delay settings and the last trip data.
See Section 17.0 for battery data and instructions on
replacing the battery.
1.0 Introduction
2.0 UL/ULC Classification
3.0 Trip Unit Power
3.1 Current Transformer (CT) Power
3.2 Battery Power

Utility Relay Company
Page 2
The AC-PRO trip unit is available with a communication
option that has a connection for a PT module.
The PT module provides breaker 3-Phase voltage
information and also provides power for the trip unit
independently from the CTs. See the Communication
Instruction Manual for more information.
Auxiliary power is optional. It can be used to change or
review the trip unit settings without using the internal battery.
Plug the 24-VAC auxiliary power pack into the auxiliary
power jack on the top of the trip unit.
The power pack is available from Utility Relay Company as
part number T-390.
The external connections are made to the top of the
AC-PRO trip unit (or the left or right side for the vertical
versions).
ACTUATOR
+
BREAKER HARNESS
PHASE
PHASE
A
PHASE
B C
NEUTRAL
QT
DISPLAY
24 VAC
POWER
AUXILIARY
KEY Use only 9V
Lithium Battery
BATTERY
COVER
Breaker Wiring Harness
See Section 4.1 Security Key
See Section 4.2
Auxiliary Power Jack
See Section 7.1.2
QT Display Jack
See Section 6.0
Battery Cover
See Section 3.2 & 17.0
Figure 4.0-1 AC-PRO®Top View
The breaker wiring harness connects the trip unit to the CTs
and actuator. The wiring harness plugs into the 10-pin
connector on the top of the trip unit and is retained with two
screws.
Pin Function Color Code
1 Actuator (+) Red
2 Actuator (-) Black
3 Phase A (Dot) Blue
4 Phase A White
5 Phase B (Dot) Yellow
6 Phase B White
7 Phase C (Dot) Brown
8 Phase C White
9 Neutral CT (Dot) Green
10 Neutral CT White
Table 4.1 Breaker Wiring Harness Pin-Out
A neutral CT wiring harness is provided as part of the neutral
CT installation kit and is only required with ground fault on a
4-wire system. The ground fault function on a 3-wire system
does not require a neutral CT.
The AC-PRO trip unit contains a security feature that only
allows someone familiar with the operation of the trip unit to
commission the trip unit or make changes to the settings. A
security key is required to change any of the settings.
The "Key" is simply a short jumper wire that is connected
between the two terminals marked “KEY” on the top of the
trip unit.
Refer to Figure 4.0-1 AC-PRO top view.
To turn the security Key "ON":
Jumper the two terminals labeled “KEY” on the top of
the trip unit.
To turn the security Key "OFF":
Remove the jumper wire.
The key allows the user to commission the trip unit or to
change the settings on a trip unit by performing the steps as
outlined in Sections 7.0 and 8.0.
The “CT Rating” also has an additional security feature as
explained in Section 7.3.
ACTUATOR
+
BREAKER HARNESS
PHASE
PHASE
A PHASE B C
NEUTRAL
QT
DISPLAY
24 VAC
POWER
AUXILIARY
KEY Use only 9V
Lithium Battery
Push Button "Key"
Breaker Escutcheon
BATTERY
COVER
Figure 4.0-2 Push Button “Key”
When the AC-PRO is installed on some breakers, the “Key”
terminal block on top of the trip unit is not readily accessible.
In those cases a short harness with a “Key” push button is
provided. The “Key” push button is installed in the breaker
escutcheon so it is easily accessible.
To turn the security Key "ON" with the “Key” button:
Push and hold the “Key” button.
To turn the security Key "OFF" with the “Key” button:
Release the “Key” button.
3.3 PT Module Power
3.4 Auxiliary Power
4.0 External Connections
4.1 Breaker Wiring Harness
4.2 Security Key

AC-PRO®With QUICK-TRIP®Instruction Manual www.utilityrelay.com
Page 3
The front view of the horizontal version of the AC-PRO trip
unit is shown in Figure 5.0-1. The front view of a vertical
version of the AC-PRO is shown in Figure 5.0-2.
AC-PRO
UTILITY RELAY COMPANY
SAVE
PUSH TO
ADJUST
DISPLAY
CONTRAST
PUSH TO VIEW
LAST TRIP DATA
AND SETTINGS
Display
Contrast
Up Down
Save Review
Pick-Up
LED
Self Test
LED
Wiring Harness Cover
Battery
CE Mark
UL Label Serial Number
(on end)
Part Number
Label
9V Lithium
Long-Life Battery
With
WITH QUICK-TRIP
AC TRIP UNIT TM
R
PICK-UP
SELF TEST OK
REVIEW
1A 0 CT 1A N CT 60Hz H490F524
PC 01168
AC-PRO
B-521H
Option
Label
Figure 5.0-1 AC-PRO®Horizontal Front View
PUSH TO VIEW
UTILITY RELAY COMPANY
LAST TRIP DATA
AND SETTINGS
AC-PRO
CONTRAST
ADJUST
DISPLAY
REVIEW
PUSH TO
PICK-UP
SELF TEST OK
SAVE
Down
LED
Self Test
Up
LED
Pick-Up Contrast
Review
Display
Save
9VLithium
Long-Life Battery
With
TM
WITH QUICK-TRIP
AC TRIP UNIT TM
Wiring Harness
Cover
Battery
1A 0 CT
1A N CT 60Hz H490F524
PC 01180
AC-PRO
B-521L
CE Mark
UL Label
Option
Serial Number
(on end) Label Part Number
Label
Figure 5.0-2 AC-PRO®Vertical Left Front View
5.0 AC-PRO
®
Front View

Utility Relay Company
Page 4
A 16-character dot matrix liquid crystal display (LCD)
provides information to the user.
The LCD is used for the following purposes:
1) Entering the CT rating and making the pick-up and time
delay settings with prompts from the display.
2) Displaying, on demand, the CT rating and the various
pick-up and delay settings.
3) Displaying, on demand, the reason for the last trip and
the currents at the time of trip.
4) Continuously displaying the actual 3-phase AC currents
on the breaker.
The Pick-Up LED is normally off. It will turn on whenever the
breaker current is above the LT Pick-up setting.
The Self Test LED is normally on. It will turn off under the
following conditions:
1) The actuator is not connected. The LCD will also
display an error message.
2) There is a checksum error in the micro-controller.
The LCD will also display an error message.
The contrast level of the LCD can be adjusted by pressing
this push button.
When the contrast push button is pressed and held, the
display will begin to get either darker or lighter. To change
direction, release the push button for more than one second,
then press and the hold the push button until the desired
contrast is achieved.
Use this push button to increase the setting values during
commissioning. When the “UP” push button is held longer
than one second, the settings are increased in fast mode.
When the maximum setting value is reached, the “UP” push
button will have no further effect on the setting value.
Use this push button to decrease the setting values during
commissioning. When the “DOWN” push button is held
longer than one second, the settings are decreased in fast
mode.
When the minimum setting value is reached, the “DOWN”
push button will have no further effect on the setting value.
Use this push button to step though the settings when in the
commissioning mode.
Holding this push button has no effect.
Use this push button to step though the settings in the
settings review mode. Also use this push button to turn the
trip unit on using battery power.
Hold this push button down to review trip counts during the
settings review.
5.2 Pick-Up LED
5.5 UP Push Button
5.6 DOWN Push Button
5.7 SAVE Push Button
5.8 REVIEW Push Button
5.4 Display Contrast
5.1 16 Character Display
5.3 Self Test LED

AC-PRO®With QUICK-TRIP®Instruction Manual www.utilityrelay.com
Page 5
AND SETTINGS
DISPLAY
CONTRAST
ADJUST
PUSH TO VIEW
LAST TRIP DATA
REVIEW
PUSH TO
SELF TEST OK
PICK-UP
UTILITY RELAY COMPANY
AC-PRO
MICRO-CONTROLLER BASED
QT-DISPLAY REMOTE DISPLAY
QUICK-TRIP ON
NC
NO
OFF
ON
Remote
Indication Contacts
Quick-Trip
On-Off Contact
in back of
Plug into
QT-DISPLAY
"QT Display"
jack
Plug into Jack
with modular connectors
8/C Cable, shielded
back of Pro-Display
2 Pole Plug into
1
2
3
AC-PRO trip unit
on breaker
QT-Display
on cubicle door
Quick-Trip ON-OFF
selector switch
Quick-Trip
QUICK-TRIP
ON OFF
Cover
Padlocking
To QT-Display
with Quick-Trip turned ON
Red LED is "ON"
for Customer Use
Selector Switch Wiring
display
16 Character
AC-PRO
UTILITY RELAY COMPANY
SAVE
PUSH TO
ADJUST
DISPLAY
CONTRAST
PUSH TO VIEW
LAST TRIPDATA
AND SETTINGS
9V Lithium
Long-Life Battery
With
WITH QUICK-TRIP
AC TRIP UNIT TM
R
PICK-UP
SELF TEST OK
REVIEW
1A 0 CT 1A N CT 60Hz H490F524
PC 01168
AC-PRO
B-521H
R
R
(100 foot maximum)
Figure 6.0-1
QUICK-TRIP®Connections
The QUICK-TRIP system is a manually controlled Zone
Selective Interlock (ZSI) 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 breaker feeding the equipment. 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 work is done, the QUICK-TRIP system is turned off
and the original selective coordination is back in effect.
The QUICK-TRIP system consists of the following
components:
1. AC-PRO trip unit with QUICK-TRIP.
2. QUICK-TRIP Display with a “QUICK-TRIP ON“ LED.
3. Padlocking selector switch mounted near the
QUICK-TRIP Display that is used to turn QUICK-TRIP
on and off.
When QUICK-TRIP is on, the following settings are enabled:
•GF QUICK-TRIP (GF QT)
•I QUICK-TRIP (I QT)
All other settings remain in effect.
The “QUICK-TRIP ON LED” provides positive indication that
the QUICK-TRIP settings are active if the LED is on.
The extra contact block on the QUICK-TRIP selector switch
can be used for local or remote indication of the QUICK-TRIP
selector switch setting.
**** IMPORTANT ****
A qualified engineer must determine the QUICK-TRIP
settings, calculate the incident energy levels and
determine the Hazard Risk Categories (HRC).
If an older Pro-Display without the “QUICK-TRIP ON”
LED is plugged into an AC-PRO with QUICK-TRIP, the
QUICK-TRIP settings will always be on.
6.0 Quick-Trip
®
System
6.1 Quick-Trip
®
Basics

Utility Relay Company
Page 6
diameter holes
Drill (2) 13/64"
QT-Display
Outline of
or alternately use
Drill 1 11/16" diameter hole
1 1/4" conduit knockout punch
1 1/4" 1 1/4"
Use 22mm switch knockout punch
Locate near PRO-DISPLAY
R
Figure 6.2-1
QUICK-TRIP®Drilling Plan
The QUICK-TRIP system is easy to install on the front of the
breaker cubicle door.
To install the QUICK-TRIP Display:
1. Find a suitable location on the cubicle door and mark
the location of the three (3) holes using the
dimensions in Figure 6.2-1.
2. Drill two (2) 13/64” mounting holes.
3. For the center hole, cut a 1-11/16” diameter hole using
a hole saw or alternately, use a 1-1/4” conduit
knockout punch.
Breaker Cubicle Door
side view
QT-Display
flat washers &
(2) 10-32 hex nuts,
lock washers
R
Figure 6.2-2
QUICK-TRIP Display Mounting
4. Attach the QUICK-TRIP Display to the front of the
cubicle door using two (2) 10-32 hex nuts, flat washers
and lock washers.
5. Connect the QUICK-TRIP Display to the AC-PRO trip
unit by plugging one end of the shielded modular
cable provided into the jack on the back of the QUICK-
TRIP Display. Plug the other end of the cable into the
“QT Display” jack on the top of the AC-PRO.
6. Route the cable so it does not interfere with the
opening or closing of the cubical door or with the
racking of the breaker between connect and
disconnect positions. Use cable ties and holders to
hold the cable in position.
To install the on/off selector switch:
1. Use a 22mm switch knock-out punch to make a hole
in the cubicle door for the selector switch. The selector
switch should be located near the QUICK-TRIP
Display.
2. Attach the selector switch, padlock attachment and
contact blocks to the cubicle door.
3. Plug the cable from the switch into the back of the
QUICK-TRIP Display.
6.2 Quick-Trip
®
Installation

AC-PRO®With QUICK-TRIP®Instruction Manual www.utilityrelay.com
Page 7
The QUICK-TRIP Display will display the same messages as
the display on the AC-PRO. It provides the capability of
viewing the breaker currents and reviewing the settings and
the last trip data without opening the breaker cubicle
door.
For security reasons, it is not possible to change any
settings from the QUICK-TRIP Display.
When the display on the QUICK-TRIP Display is off, push
the “REVIEW” button to power the QUICK-TRIP Display
from the internal battery in the AC-PRO. The following
information will be available:
•Last trip data including the type of trip and the currents
•Pushing the “REVIEW” button will display the trip log
•Continuing to push the “REVIEW” button will step
through the settings
•The “SELF TEST OK” LED will indicate proper operation
•The “QUICK-TRIP ON” LED will indicate the on/off status
of the QUICK-TRIP settings
When the display on the QUICK-TRIP Display is on, the
phase currents will be displayed (if greater than 10% of the
CT tap). The following information will also be available:
•The “PICK-UP” LED will indicate if phase currents are
above the Long Time pick-up setting
•The “SELF TEST OK” LED will indicate proper operation
•The “QUICK-TRIP ON” LED will indicate the on/off status
of the QUICK-TRIP settings
Pushing the “REVIEW” button will display:
•Last trip data including the type of trip and the currents
•Pushing the “REVIEW” button will display the trip log
•Continuing to push the “REVIEW” button will step
through the settings
Before the AC-PRO trip unit is put into service, it must first
be commissioned so it will function. This requires the user to
enter all of the pick-up and delay settings into the unit.
The commissioning process normally takes less than a few
minutes to complete.
**** IMPORTANT ****
The trip unit will NOT FUNCTION as it is shipped from
the factory. The user must first COMMISSION the unit as
outlined in this Section to make it functional.
After the AC-PRO is installed on the breaker, it must be
commissioned as follows:
1)Connect the security key (see Section 4.2)
2)Push the "REVIEW" push button to power-up the trip
unit. The trip unit will alternately display the following:
ENTER DATA
SERIAL # XXXXXXX
Press the “SAVE” push button. The following will be
displayed:
PROD: H4.90F5.26
Press the “SAVE” push button to begin the commissioning
process.
3) Enter the appropriate CT tap, pick-up and delay
settings using the "UP", "DOWN" and "SAVE" push
buttons.
4) Remove the security key (see Section 4.2).
Sections 7.1 through 7.20 go over the commissioning
process in greater detail.
****NOTE****
An additional security feature is provided to avoid
accidentally changing the CT tap setting. See Section 7.3.
In normal service, the AC-PRO trip unit is powered directly
from the breaker mounted CTs.
For commissioning, the AC-PRO trip unit can be powered-up
in either of the following two ways.
Press the "REVIEW" button to power-up the trip unit using
the internal battery.
The trip unit is designed to shut off automatically if none of
the 4 lower push buttons on the face of the unit are pressed
for 30 seconds. It is best to have all the desired settings
readily available before commissioning the unit when using
the battery.
If the unit shuts down before the commissioning process is
completed, the process must be started again from the
beginning.
Apply 24 VAC to the "auxiliary power" jack located on the top
of the trip unit using the Utility Relay auxiliary power pack.
(Utility Relay Company part number T-390).
By applying external power, the unit will stay energized as
long as necessary to complete the commissioning process.
The following will be displayed if the security key is not
already connected:
SECURITY KEY OFF
Connect the security key to continue the commissioning
process (See Section 4.2).
6.3 Quick-Trip
®
& Pro-Display Operation
7.0 Commissioning the AC-PRO
®
7.1 Powering-Up the Trip Unit
7.2 Security Key
7.1.1 Internal Battery
7.1.2 External Power

Utility Relay Company
Page 8
After the security key is connected, the following will be
displayed:
CT RATING XXXXA
Where "XXXX" represents the CT rating in amps. The CT
rating can range from 50 amps to 5,000 amps in 25 amp
steps and 5250 amps to 6000 amps in 250 amp steps.
The CT rating entered into the trip unit must correspond to
the actual rating of the phase and neutral CT tap that the trip
unit is connected to.
A security feature is provided so the CT rating will not be
accidentally changed later.
The CT security feature must be used to enter the initial CT
rating or to change the CT rating.
***To Activate the CT Security Feature***
In the commissioning mode and when the CT rating is
displayed:
Simultaneously push and release both the "SAVE"
and "REVIEW" push buttons
This allows the CT rating to be changed.
With the security feature activated, press and hold the "UP"
or "DOWN" push button as required until the correct CT
rating is displayed.
Press the "SAVE” push button to continue.
The following will be displayed:
LT PICK-UP XXXXA
Where "XXXX" represents the LT Pick-Up setting in amps.
The LT Pick-Up setting ranges from 20% to 100% of the CT
rating. This setting is adjustable in 5 amp steps (50 amp
steps for 5250 to 6000 amp CTs and 0.5 amp steps for 50 to
200 amp CTs).
Press and hold the "UP" or "DOWN" push button as required
until the correct LT Pick-Up setting is displayed.
Press the "SAVE" push button to continue.
The following will be displayed:
LT DELAY XX.XS
Where "XX.X" represents the LT Delay band. The LT Delay
band is labeled by the number of seconds to trip at 6 times
the LT Pick-Up setting.
The LT Delay setting ranges from 2.0 to 30.0 seconds in
steps of 0.5 seconds. This provides 57 LT Delay bands.
Please note that the LT trip time is not a constant value, but
is a function of breaker current. For lower currents the trip
time is longer, and for higher currents the trip time is shorter.
The trip time is only equal to the LT Delay setting when a
current 6 times the LT Pick-Up setting is applied. See the
time-current curves in Figure 18.2.
Press and hold the "UP" or "DOWN" push button as required
until the correct LT Delay setting is displayed.
Press the "SAVE" push button to continue.
The following will be displayed:
ST PICK-UP OFF
If the ST function is not desired, press the "SAVE" push
button and go to Step 7.9.
If the ST function is desired, press the "UP" push button and
the following will be displayed:
ST PICK-UP XXXXA
Where "XXXX" represents the ST Pick-Up in amps.
The ST Pick-Up setting ranges from 150% to 1200% of the
LT Pick-Up setting in 100 amp steps (1000 amp steps for
5250 to 6000 amp CTs and 10 amp steps for 50 to 200 amp
CTs). Press and hold the "UP" or "DOWN" push button as
required until the correct ST Pick-Up setting is displayed.
Press the "SAVE" push button to continue.
If the ST function is not off, then the following will be
displayed:
ST DELAY .XXS
Where ".XX" represents the ST Delay.
The ST Delay settings are .07, .10, .15, .20, .30 and .40
seconds.
Press and hold the "UP" or "DOWN" push button as required
until the correct ST Delay setting is displayed.
Press the "SAVE" push button to continue.
The I²T function adds a ramp to the ST delay if required for
coordination purposes as shown in the Overload TCC in
Figure 18.2.
If the ST function is not off, then the following will be
displayed:
ST I SQ T XXX
Where "XXX" represents ON or OFF.
If the ST I²T ramp is desired, press the "UP" push button. If
the ST I²T ramp is not desired, press the "DOWN" push
button.
Press the "SAVE” push button to continue.
7.3 CT Rating
7.4 Long Time (LT) Pick-Up Setting
7.5 Long Time (LT) Delay Setting
7.6 Short Time (ST) Pick-Up Setting
7.7 Short Time (ST) Delay Setting
7.8 Short Time (ST) I
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The following will be displayed:
I PICK-UP XXXXXA
Where "XXXXX" represents the I Pick-Up in amps.
The I Pick-Up setting ranges from 150% to 1200% of the LT
Pick-Up setting in 100 amp steps (1000 amp steps for 5250
to 6000 amp CTs and 10 amp steps for 50 to 200 amp CTs).
Press and hold the "UP" or "DOWN" push button as required
until the correct I Pick-Up setting is displayed.
If the I function is not desired and the ST function is not off,
press the "DOWN" push button until the following is
displayed:
I PICK-UP OFF
**** NOTE ****
The trip unit does not allow setting both the ST and the I
functions off at the same time.
Press the "SAVE" push button to continue.
If the GF function is not desired, then press the "DOWN"
push button until the following is displayed:
GF PICK-UP OFF
If the GF function is desired, press the "UP" push button and
the following will be displayed:
GF PICK-UP XXXXA
Where "XXXX" represents the GF Pick-Up setting in amps.
The minimum GF Pick-Up setting is 20% of the CT rating
with 10 amp steps (1 amp steps for 50 to 200 amp CTs).
The maximum value is 200% of the CT rating or 1200 amps,
whatever is lower.
Press and hold the "UP" or "DOWN" push button as required
until the correct GF Pick-Up setting is displayed.
Press the "SAVE" push button to continue.
If the GF function is not off, then the following will be
displayed:
GF DELAY .XXS
Where ".XX" represents the GF Delay.
The GF Delay settings are .10, .20, .30, .40 and .50
seconds.
Press and hold the "UP" or "DOWN" push button as required
until the correct GF Delay setting is displayed.
Press the "SAVE” push button to continue.
The I²T function adds a ramp to the GF delay if required for
coordination purposes as shown in the Ground Fault TCC in
Figure 18.3.
If the GF function is not off, then the following will be
displayed:
GF I SQ T XXX
Where "XXX" represents ON or OFF.
If the GF I²T ramp is desired, press the "UP" push button. If
the GF I²T ramp is not desired, press the "DOWN" push
button.
Press the "SAVE” push button to continue.
**** NOTE ****
On a 4-wire system, a neutral CT must be installed to
avoid nuisance GF trips.
**** IMPORTANT ****
To implement GF protection on the main breakers and
the tie breaker of a double ended substation, contact
Utility Relay Co.
The following will be displayed:
U/B PICK-UP OFF
If the U/B function is not desired, then press the "SAVE”
push button and go to Step 7.15.
If the U/B function is desired, press the "UP" push button
and the following will be displayed:
UB PICK-UP XX%
Where "XX" represents the U/B Pick-Up setting in
percentage. The minimum and maximum UB Pick-Up setting
is 20% and 50% in steps of 5 percentage points.
Press and hold the "UP" or "DOWN" push button as required
until the correct U/B Pick-Up setting is displayed.
Press the "SAVE" push button to continue.
**** NOTE ****
The U/B function should not be confused with the GF
function.
The U/B function is a motor protection function and
should ONLY be used on breakers feeding a large
3-phase motor where currents are normally balanced.
7.9 Instantaneous (I) Pick-Up Setting
7.10 Ground Fault (GF) Pick-Up Setting
7.11 Ground Fault (GF) Delay Setting
7.12 Ground Fault (GF) I
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7.13 Phase Unbalance (U/B) Pick-Up

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If the U/B function is not off, then the following will be
displayed:
UB DELAY XXS
Where "XX" represents the U/B Delay. The U/B Delay setting
ranges from 1 to 60 seconds in steps of 1 second.
Press and hold the "UP" or "DOWN" push button as required
until the correct U/B Delay setting is displayed.
Press the "SAVE” push button to continue.
This setting applies only to AC-PRO+trip units with the
communication option and will not be displayed on non-
communicating trip units.
Each communicating trip unit that shares the same twisted
pair must have a unique address.
ADDRESS XXX
Where "XXX" represents the trip unit address and ranges
from 1 to 127 in increments of 1. Press the "UP" or "DOWN"
push button as required until the desired address setting is
displayed.
Press the "SAVE” push button to continue.
NOTE: Two trip units can have the same address as long as
they are not connected to the PC, Ethernet converter,
RS-232 converter or Local Communications Interface (LCI)
via the same twisted pair cable.
This setting applies only to AC-PRO+trip units with the
communication option and will not be displayed on non-
communicating trip units.
The reply delay setpoint is the minimum delay between the
trip unit’s receipt of a MODBUS packet and its reply.
The reply delay can be either 5 or 10 milliseconds. The
factory default is 5 milliseconds.
REPLY DELAY XXMS
Where "XXMS" represents either 5 or 10 milliseconds. Press
the "UP" or "DOWN" push button as required until the
desired delay setting is displayed.
Press the "SAVE” push button to continue.
This setting applies only if the QUICK-TRIP Display and
selector switch are installed. See Section 6.0 for details.
If the QT GF function is not desired, then press the "DOWN"
push button until the following is displayed:
GF QT PICK-UP OFF
If the QT GF function is desired, press the "UP" push button
and the following will be displayed:
GF QT PICK-UP XXXXA
Where "XXXX" represents the QT GF Pick-Up setting in
amps.
The minimum QT GF Pick-Up setting is 20% of the CT rating
with 10 amp steps (1 amp steps for 50 to 200 amp CTs).
The maximum value is 200% of the CT rating or 1200 amps,
whatever is lower.
Press and hold the "UP" or "DOWN" push button as required
until the correct QT GF Pick-Up setting is displayed.
The QT GF function has a non-adjustable short delay time
as shown in Figure 18.4.
Press the "SAVE" push button to continue.
This setting applies only if the QUICK-TRIP Display and
selector switch are installed. See Section 6.0 for details.
The following will be displayed:
I QT PICK-UP XXXXXA
Where "XXXXX" represents the QT I Pick-Up in amps.
The QT I Pick-Up setting ranges from 150% to 1200% of the
LT Pick-Up setting in 100 amp steps (1000 amp steps for
5250 to 6000 amp CTs and 10 amp steps for 50 to 200 amp
CTs).
Press and hold the "UP" or "DOWN" push button as required
until the correct QT I Pick-Up setting is displayed.
The QT I function does not have an off setting. It is turned on
or off using the QUICK-TRIP ON-OFF selector switch. If the
Pro-Display with QUICK-TRIP is not installed, then this
function is always off.
Press the "SAVE" push button to continue.
7.14 Phase Unbalance (U/B) Delay 7.17 Quick-Trip
®
Ground Fault (QT GF)
7.18 Quick-Trip
®
Instantaneous (QT I)
7.15 Address
7.16 Reply Delay

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Page 11
The AC-PRO trip unit has a Thermal Memory feature for the
following protective functions:
Long Time (LT)
Short Time (ST)
Ground Fault (GF)
Thermal Memory can be turned on or off for the LT and ST
protective functions only.
Thermal Memory for the GF function is always on and
cannot be turned off. The GF Thermal Memory feature
provides protection against “sputtering” ground faults.
Except for unusual conditions, it is recommended that
the Thermal Memory feature for LT and ST should be
turned on.
Cycling overloads that are not above the LT Pick-Up long
enough to cause a trip can still lead to thermal damage to
wiring and equipment. With Thermal Memory turned on a
cycling overload can still produce a LT trip to protect cables
and equipment even if any individual overload event did not
persist long enough to directly cause a LT trip.
With Thermal Memory turned off, an overload that drops
below the LT Pick-Up will reset the LT trip register. If the
current goes above the LT Pick-Up again, the LT trip register
starts from zero.
The above is also true for the ST function.
The following will be displayed:
THERMAL MEM XXX
Where "XXX" represents Thermal Memory ON or OFF for
the LT and ST functions.
If Thermal Memory for LT and ST is desired, press the "UP"
push button. If Thermal Memory for LT and ST is not
desired, press the "DOWN" push button. Thermal Memory
for LT and ST can not be individually turned on or off.
Press the "SAVE” push button to continue.
The following will be displayed:
SAVE IF DONE
REVIEW TO REVIEW
If it is desired to review the setting, push the “REVIEW” push
button. Make any changes necessary using the “UP” or
“DOWN” push buttons. As before, use the “SAVE” push
button to move to each new setting.
If the settings are as desired, push the “SAVE” push button.
The following will be displayed:
REMOVE KEY TO
COMMISSION UNIT
Remove the “key” (See section 4.2). The settings will be
saved in the non-volatile EEPROM memory.
If the commissioning process was performed using the
internal battery, the unit will turn itself off.
If external power was used to power the trip unit during the
commissioning process, the following will be displayed:
LOW CURRENT
The commissioning process is complete.
7.20 Exit Procedure
7.19 Thermal Memory

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Page 12
**** IMPORTANT ****
While it is possible to make changes to the settings with
the breaker in service, it is strongly recommended that
the breaker must be removed from service while
making these changes since the breaker is energized
and the trip unit will not provide protection during a small
part of this process.
After the trip unit is commissioned, settings can easily be
changed in the following manner.
Connect the security key. See Section 4.2.
Power up the trip unit by pressing "REVIEW" or by applying
external power as described in Section 7.1.
Press the “REVIEW” push button. The following will be
displayed:
ENTER DATA
SERIAL # XXXXXXX
Press the "SAVE” push button.
Make any necessary changes using the "UP" or "DOWN"
push buttons. Use the "SAVE" push button to move to each
new setting.
**** IMPORTANT ****
The CT rating entered in the trip unit must match the
rating of the CT the trip unit is connected to.
A security feature protects against accidentally changing
the CT rating. See Section 7.3.
After going through all the settings, the following will be
displayed.
SAVE IF DONE
REVIEW TO REVIEW
If it is desired to review the setting, push the "REVIEW" push
button. Make any changes necessary using the "UP" or
"DOWN" push buttons. As before, use the "SAVE" push
button to move to each new setting.
If the settings are as desired, push the "SAVE” push button.
The following will be displayed:
REMOVE KEY TO
COMMISSION UNIT
Remove the security key (See Section 4.2). The settings will
be saved in the non-volatile EEPROM memory.
The Settings have been changed.
Remember, if the trip unit loses power during this process,
the old settings will be retained and the process must be
repeated.
8.0 Changing Settings

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Page 13
The AC-PRO has an especially useful last trip data recall
and trip counter feature.
After a breaker trip, the trip unit will be able to display the
type of trip (i.e. LT, ST, I, GF, U/B, GF QT or I QT as
applicable) along with the currents at the time of trip. This
information is saved in the non-volatile FLASH memory and
is available immediately after a trip or anytime thereafter.
**** NOTE ****
Only the complete data from the last trip is saved. The
second time the breaker trips, the new trip data is written
over the first trip data. The trip counter is also updated at
this time.
Push the “Review” push button to recall the Last Trip Data
and settings. The following will be displayed if there was no
last trip:
NO LAST TRIP
If there was a last trip, the following messages will
alternately display showing the cause of the trip and the
currents at the time of trip. The messages alternate at a one
second interval rate:
LAST TRIP XXXX
PHASE A XXXXXA
PHASE B XXXXXA
PHASE C XXXXXA
GF XXXXXA
If GF current is greater than 2 times the CT Rating, the
following will be displayed for GF:
GF>2XCT RATING
Only those phase currents greater than 10% of the CT
Rating will be displayed.
U/B YY%
The U/B percentage will be displayed if on and the U/B is
greater than 4%.
The text “XXXX” is the type of tripping event (i.e. LT, ST, I,
GF, U/B, GF QT or I QT as applicable) and “XXXXX” is the
magnitude of the current at the time of trip for each phase.
The text “YY” is the percentage of unbalance at trip.
Press the “REVIEW” push button again to view the following
message:
HOLD <REVIEW> TO
VIEW TRIP COUNTS
If the “REVIEW” button is pushed again and held down for
longer than 2 seconds, each type of trip is displayed along
with the number of times that trip has occurred. If the
“REVIEW” button is pressed, but not held for 2 seconds, the
trip count is skipped and the settings are displayed.
INST TRIPS: XX
Push the “REVIEW” Button.
LT TRIPS: XX
Push the “REVIEW” Button.
ST TRIPS: XX
Push the “REVIEW” Button.
GF TRIPS: XX
Push the “REVIEW” Button.
U/B TRIPS: XX
Push the “REVIEW” Button.
GF QT TRIPS:
XX
Push the “REVIEW” Button.
I QT TRIPS: XX
The text “XX” is the number of trips since last commissioned
or reset.
By pressing the "REVIEW" push button the present settings
programmed in the trip unit can be stepped through in
sequence.
**** NOTE ****
Pushing the "SAVE", "UP" or "DOWN" push buttons
during last trip data recall has no effect because the key is
not installed.
When pushing "REVIEW” after the last setting, the trip unit
will turn it self off.
If the "REVIEW" push button is not pressed for about 30
seconds, the trip unit will also turn off.
9.0 Last Trip Data Recall

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Page 14
Breaker Current Less than about 8% of CT Rating:
With all phase currents less than about 8%, the trip unit is
not receiving enough energy from the CTs to operate and
the display will be blank (except for the communication
version with a PT module).
Breaker Current Less than 12.5% of CT Rating:
When the currents are greater than about 8% but less than
about 12.5% of the CT rating, the display will show the
following:
LOW CURRENT
Breaker Current Greater than 12.5% of CT Rating:
If the breaker current is greater than about 12.5% of the CT
rating but less than the LT pick-up value, the following will be
alternately displayed on the LCD at one second intervals:
PHASE A XXXXA
PHASE B XXXXA
PHASE C XXXXA
GF XXXXA
Where "XXXX" is the current in amps for that phase or
ground fault current.
Only those currents above 12.5% will be displayed. The GF
current will only be displayed if the GF function is on.
Breaker Current Greater than the LT pick-up:
When the trip unit detects a phase overload situation, the
“PICK-UP” LED on the front of the trip unit will go on, and the
following will alternately be displayed on the LCD at one
second intervals:
OVERLOAD
PHASE A XXXXA
PHASE B XXXXA
PHASE C XXXXA
GF XXXXA
Where "XXXX" is the current in amps for that phase or
ground fault current.
Only those currents above 12.5% will be displayed. The GF
current will only be displayed if the GF function or QT GF
function is on.
A "primary injection" test is recommended as the final test of
the AC-PRO retrofit.
It is not necessary to turn off the Unbalance (U/B) function
when doing a single-phase primary injection test.
If used, GF must be temporarily turned off when testing the
other trip functions.
Before proceeding with the normal primary injection tests,
the trip unit must be commissioned to make it functional. See
Section 7.0 for the commissioning procedure.
It is best to use the final pick-up and time delay settings if
they are known. If not, use typical settings for the primary
injection test.
Make sure GF is temporarily turned off. The U/B function can
be left on if desired.
Make sure GF is temporarily turned off. The U/B function can
be left on.
To test the LT Pick-Up, increase the current until the “Pick-
Up” LED illuminates.
The injected current should correspond to the programmed
LT Pick-Up setting. Verify that the correct phase is indicated
on the LCD display.
To test the LT trip time, first calculate the trip time based on
the value of the test current that will be applied. Use the
formula in Section 15.1 or the chart in Section 12.3..
**** NOTE ****
A simple shortcut is to note that the trip time (center
of the curve) at 3 times the LT pick-up current is 4
times the LT Delay setting.
For example:
If LT Pick-Up is 1600A and Delay is 10.0S, then the
trip time at 4800A (3 times 1600A) is 40 sec. (4 times
10 sec).
10.0 Normal Operations 11.0 Testing
11.1 Commission the Trip Unit
11.2 LT Trip Test

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Page 15
Make sure GF is temporarily turned off. The U/B function can
be left on.
To test the ST Pick-Up, temporarily set ST I2T off and apply
a short pulse of current that is 10% or 20% less than the ST
Pick-Up setting. Continue applying short pulses of current
while increasing the current for each pulse until a ST trip
occurs. The first current where a ST trip occurred is the ST
Pick-Up.
To test the ST Delay, turn ST I2T on again (if applicable) and
apply a current that is at least 10% greater than the ST Pick-
Up current.
The trip time should fall within the time band shown on the
Time-Current curves.
Make sure GF is temporarily turned off. The U/B function can
be left on.
Test the Instantaneous Pick-Up and trip time in the same
manner as ST in Section 11.3.
With GF Pick-Up and Delay set to the required values,
testing any one of the three poles will provide a GF trip.
Test the GF Pick-Up and trip time in the same manner as ST
in Section 11.3.
To test QT GF the QUICK-TRIP Display must be connected
to the AC-PRO trip unit and the QUICK-TRIP ON-OFF
selector switch must also be connected as shown in
Figure 6.0-1.
With QT GF Pick-Up set to the required value and the
QUICK-TRIP selector switch turned to the on position, testing
any one of the three poles will provide a QT GF trip.
Test the QT GF Pick-Up and trip time in the same manner as
the normal GF function.
The breaker CT phasing is only important for the GF function
and the QT GF function. If one of the breaker mounted CTs
has reversed polarity, a nuisance GF or QT GF trip will most
likely occur. With the breaker in service on a 3-phase
system, the last trip data with a reversed polarity CT will
show the GF current as approximately two times the
phase currents.
Since primary injection testing normally tests only one phase
at a time, a breaker CT with reversed polarity will not be
detected with the normal tests. By using the following
method, a primary injection test set can be used to test for
proper CT polarity.
Figures 11.7-1 and 11.7-2 show a method to verify that the
breaker CT polarities match. The setup in Figure 11.7-1
verifies that the CT polarities of Phase A and Phase B
match. The setup in Figure 11.7-2 verifies that the CT
polarities of Phase B and Phase C match.
It is only necessary to inject a current slightly greater than
the GF Pick-Up setting and to verify that a GF trip does not
occur.
To Test Set
Breaker
Jumper load side of Phase A & B poles
"A" "B" "C"
CTs
Apply current slightly greater
If Phase A & B phasing match,
a GF trip will not occur.
than GF Pick-Up to the breaker line side.
Figure 11.7-1 Phase A & B, CT Phasing Test
To Test Set
"B""A"
Jumper load side of Phase B & C poles
Breaker
CTs
than GF Pick-Up to breaker line side.
a GF trip will not occur.
If Phase B & C phasing match,
Apply current slightly greater
"C"
Figure 11.7-2 Phase B & C, CT Phasing Test
If a GF trip does occur, determine which CT has the
reversed polarity. Reverse the secondary connections at the
CT to correct the reversed polarity.
The breakers shown in Figures 11.7-1 & 11.7-2 have the
CTs on the load side. Use exactly the same method if the
CTs are on the breaker line side or if they are staggered.
If a neutral CT is used, it’s polarity must match the polarity of
the breaker mounted CTs. Testing for proper neutral CT
polarity is more difficult because it is mounted remote from
the breaker.
11.3 ST Trip Test
11.4 I Trip Test
11.5 GF Trip Test
11.6 QT GF Trip Test
11.7 CT Phasing Test for GF

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Page 16
To test QT I the QUICK-TRIP Display must be connected to
the AC-PRO trip unit and the QUICK-TRIP ON-OFF selector
switch must also be connected as shown in Figure 6.0-1.
With QT I Pick-Up set to the required value and the QUICK-
TRIP selector switch turned to the on position, test all three
breaker poles in the same manner as the normal I function.
The U/B trip function is not easy to test with a single phase,
high current test set.
Figure 11.9-1 illustrates a method to test the U/B trip
function. It requires using cable or bus to jumper the breaker
poles as shown. This generates an unbalanced current of
50% or slightly more depending on how equally the current
is split between the two poles.
It is only necessary to inject a current equal to 20% or 30%
of the CT rating for this test. It is only possible to test the U/B
trip time and not the U/B Pick-Up with this method.
Breaker
Jumper 3 poles
Jumper 2 poles
100% Current
50% Current
50% Current
Unbalance = 50%
"A" "B" "C"
CTs
Figure 11.9-1 U/B Test
After completing the primary or secondary injection tests, it is
important to erase the last trip data from the memory of the
trip unit.
**** IMPORTANT ****
Erase the last trip data from the memory of the trip unit
after completing the primary or secondary injection tests.
To erase the memory in the trip unit after completing the
primary or secondary injection tests, use the following
method:
1) The trip unit can be either off or powered-up.
2) Push the "REVIEW" button to display the last trip data.
3) While the last trip data is flashing, push and hold both
the "UP" and "DOWN" push buttons.
4) Continue to hold the "UP" and "DOWN" buttons and
push the "SAVE" button. Release all buttons. The
following will be displayed:
NO LAST TRIP
**** IMPORTANT ****
If the last trip data is not erased after the primary or
secondary injection test, the operating personnel may later
assume that the breaker interrupted a fault at some time in
the past when they recall the last trip data. The trip counter
will also have misleading data.
11.8 QT I Trip Test
11.9 U/B Trip Test
11.10 Erase Last Trip Data