Ametek PF3 SCR Series Operation and maintenance manual

SCR POWER CONTROLLER
Instruction, Operation and
Maintenance Manual
Number: 9100034
Revision 3
530 Lakeview Plaza Blvd, Ste C
Worthington, Ohio, USA 43085
Toll F re e : 1 - 8 88- PWR- C NTL (7 9 7 -26 85)
Ph o n e: 61 4 -3 0 8-550 0
Fa x : 614 - 3 08 - 5506
Web: w w w .hd rpow e r. c o m
PF3 SCR Series
60-1200 Amperes
Three-phase
Phase-fired

This manual applies to all Model PF3 SCR Power Controls. Former PF1/PF3 manual – 9100014 has been
replaced with this manual.
For the support representative nearest you, please call Ametek HDR Power Systems main office at (614)-308-
5500.
Revision 1 September 2014 Initial Release
Revision 2 July 2015 Revised Address
Revision 3 Aug 2022 General Revision
 2022 by Ametek HDR Power Systems. No portion of this document may be reproduced either mechanically or electronically without the
prior consent of Ametek HDR Power Systems.

PF3 SCR Power Controller Table of Contents
Rev 3 Ametek HDR Power Systems i
TABLE OF CONTENTS
IMPORTANT SAFETY INSTRUCTIONS ............................................................................................................. 1
CHAPTER 1 - DESCRIPTION .............................................................................................................................. 3
1.1 General Description 3
1.2 Application 3
1.3 Operation 3
1.4 Specification 3
CHAPTER 2 - OPTIONS ...................................................................................................................................... 5
2.1 General 5
2.2 Option OC (Three-Phase Overcurrent Trip) 5
2.3 Option CL/OC (Current Limit/Overcurrent Trip) 5
2.4 Option CR/OC (Current Regulation/Overcurrent Trip) 5
2.5 Option PR (Power Regulation with Current Limit) 6
2.6 Option ER (Extended Ramp) 6
2.7 Option LG (Lug Kit) 6
2.8 Additional Options 6
CHAPTER 3 - INSTALLATION ............................................................................................................................ 7
3.1 Mounting the PF3 7
3.2 Input/Output Wiring 7
3.3 Fan Wiring (applicable to models rated 90 A and higher) 7
3.4 Wiring Overtemperature Contacts 8
3.5 Command Signal Input 8
3.6 Determining Line Frequency 9
3.7 Voltage Changeover 9
3.8 Options 10
CHAPTER 4 - OPERATION ............................................................................................................................... 13
4.1 General 13
4.2 Front Panel Indicators 13
4.3 Command Input Control 13
4.4 Remote Manual Control with a Potentiometer 14
4.5 Auto/Manual Control with a Controller and Remote Potentiometer 15
4.6 On/Off Control 16
4.7 Shutdown 17
4.8 Unbalance Alarm 17
4.9 Shorted SCR Alarm 19
CHAPTER 5 – OPTIONS SETUP ...................................................................................................................... 21
5.1 Option OC (Overcurrent Trip) 21
5.2 Option CL/OC (Current Limit/Over Current Trip) 21
5.3 Option CR/OC (Current Regulation/Over Current Trip) 22
5.4 Option PR 22
CHAPTER 6 - THEORY...................................................................................................................................... 23
6.1 Functional Description 23
6.2 Overview of the PF3 23
6.3 Digital Firing Control Circuit 23
6.4 Pulse-Train Firing 23
6.5 Phase-Lock Loop 23
6.6 SPAN and ZERO Controls 24
6.7 Voltage-Squared Feedback 24

Table of Contents PF3 SCR Power Controller
ii Ametek HDR Power Systems Rev 3
6.8 Shut-down 24
6.9 Soft-Start Circuit 24
CHAPTER 7 – TROUBLESHOOTING ............................................................................................................... 25
7.1 Customer-Service Program 25
7.2 Troubleshooting Typical Symptoms 25
7.3 Static Precautions when Servicing 25
7.4 Environmental Problems 26
7.5 Input Power and Load Connections 26
7.6 Correcting Troubles in the PF3 Itself 27
CHAPTER 8 - SERVICE ..................................................................................................................................... 29
8.1 Communication Procedures 29
8.2 Spare Parts Orders – Routine or Emergency 29
8.3 Spare Parts List 30
8.4 Drawing List 31
CHAPTER 9 – WARRANTY POLICY ................................................................................................................ 33
9.1 Warranty 33
9.2 In-house Repair Services 33
APPENDIX .......................................................................................................................................................... 35
Appendix A – System Schematic 35
Appendix B – 60-225 A Outline 36
Appendix C – 350-500 A Outline 37
Appendix D – 650 A Outline 38
Appendix E – 800-1200 A Outline 39
Appendix F – Declaration of Conformity 40

PF3 SCR Power Controller Table of Contents
Rev 3 Ametek HDR Power Systems iii
TABLE OF CONTENTS
Par. Title Page
ILLUSTRATIONS
Figure 3.1 Fan and Thermostat Connections .................................................................................................. 8
Figure 3.2 Isolated/Non-Isolated Switches ...................................................................................................... 9
Figure 3.3 T1, T2 Transformer Connections ................................................................................................... 9
Figure 3.4 Current Transformer Connections ............................................................................................... 10
Figure 3.5 Typical PF3 Line and Load Connections ..................................................................................... 11
Figure 4.1 Control Panel .................................................................................................................................. 13
Figure 4.2 Process Controller Input Connections ........................................................................................ 14
Figure 4.3 Remote Control with a Potentiometer ......................................................................................... 15
Figure 4.4 Auto/Man Control with Controller and Remote Potentiometer ................................................. 16
Figure 4.5 On/Off Control ................................................................................................................................ 16
Figure 4.6 Shutdown Control .......................................................................................................................... 17
Figure 4.7 Unbalance Alarm Board ................................................................................................................ 18
Figure 4.8 Shorted SCR Alarm Board ............................................................................................................ 19
Figure 4.9 Unbalance Block Diagram ............................................................................................................. 20
Figure 5.1 Current Limit/Trip Board ............................................................................................................... 21
Figure 6.1 AC Switch and SCR On-time ......................................................................................................... 23
TABLES
Table 1.1 PF3 Model Number Breakdown........................................................................................................ 3
Table 1.2 General Specifications of PF3 Models ............................................................................................ 4
Table 3.1 Wire Size Information ........................................................................................................................ 7
Table 3.2 Transformer Voltage Wiring ........................................................................................................... 10
Table 7.1 Troubleshooting Chart (Symptoms and Solutions) ..................................................................... 27
Table 7.2 Torque Specifications ..................................................................................................................... 27
Table 8.1 PF3 Spare Parts List ........................................................................................................................ 30
Table 8.2 PF3 Drawing List ............................................................................................................................. 31

Table of Contents PF3 SCR Power Controller
iv Ametek HDR Power Systems Rev 3

PF3 SCR Power Controller Safety Instructions
Rev 3 Ametek HDR Power Systems 1
SAVE THESE INSTRUCTIONS
IMPORTANT SAFETY INSTRUCTIONS
WARNING
Observe all warnings and cautions in this manual. Failure to do so may result in serious injury or death.
Refer all service to properly trained and qualified service personnel. Never work alone.
Lethal voltages exist on exposed heat sinks even if the power controller is turned off. Remove power and lock
out power before attempting any service.
This manual contains important safety instructions that must be followed during the installation and
maintenance of the SCR Power controller. Read this manual thoroughly before attempting to operate this
Power controller.
An appropriate branch circuit fused disconnect or circuit breaker with this Power Controller is required to
ensure the safety of operating personnel.
CAUTION
HAZARDOUS VOLTAGES exist at the Power Controller Heat Sinks and at the Load, AT ALL TIMES, when
input voltage is connected. This condition exists even when the Power Controller is set to deliver zero output.
Printed circuit boards contain sensitive components that can be damaged by electrostatic discharge (ESD).
Observe precautions for handling electrostatic sensitive devices. Reference Maintenance and Troubleshooting
(Chapter 7) of this manual for details
In case of fire, use a dry chemical fire extinguisher to put out the fire. Using a liquid fire extinguisher may
cause electric shock.
The SCR Power Controller makes use of components dangerous for the environment (electronic printed circuit
boards, electronic components). The components removed must be taken to specialized collection and
disposal centers.
E151547
100kA SCCR
IEC 947-5-1

Safety Instructions PF3 SCR Power Controller
2 Ametek HDR Power Systems Rev 3

PF3 SCR Power Controller Description
Rev 3 Ametek HDR Power Systems 3
CHAPTER 1 - Description
1.1 General Description
The PF3 is a Three-phase, phase-fired power controller, and can operate with a wide variety of input
signals and line voltages up to 575 Vac and currents ranging from 60 through 1200 amperes. The
PF3’s output voltage is proportional to its input signal. The PF3 features pulse-train firing which
provides high immunity to possible SCR firing disturbances, and phase-lock loop circuitry which
ensures line frequency synchronization. Other features are input isolation from ground, soft-start, and
automatic restart circuitry. Terminals are provided to permit connection of a variety of external control
methods. A more detailed description of the features mentioned above is provided in Chapter 6 of this
manual.
1.2 Application
Phase-Fired SCR Power Controllers provide infinitely variable firing angles for precise control of three-
phase power to resistive or inductive loads. This precise control is essential for transformer coupled
loads or loads with great resistance changes due to temperature or start-up. Phase-Fired units may
also be used on straight resistive loads as well, but the lower power factor and higher harmonics may
present a problem to other equipment mounted nearby. A zero fired model would be a better choice.
1.3 Operation
The PF3 accomplishes power control by the switching action of a pair of inverse-parallel power SCRs.
The switching, or gating, of the SCRs is controlled by a digital firing control circuit synchronized “in
phase” with line frequency (either 50 or 60 Hz). A soft-start (approximately a 12 cycle ramp) feature is
standard that allows the Power Controller to fire into the primary of a transformer or to control power to
heating elements which have a large resistance change during start-up. The output may be adjusted
by the on-board multi-turn potentiometers or by a voltage or current signal from a process controller.
ZERO and SPAN controls allow the user to calibrate the SCR unit's output to the process command
signal. Terminals are available for connection of a remote manual potentiometer.
1.4 Specification
Specifications for the PF3 SCR power controller are given in Tables 1.1 and 1.2.
Table 1.1 PF3 Model Number Breakdown
PF3 – 480 – 225 – CR – UB – 01
NOTE: N.O. Thermostat is included in current ratings above 60 A.
120 Vac - 120
240 Vac - 240
400 Vac - 400
480 Vac - 480
575 Vac -
575
60 A rms - 60
90 A rms - 90
120 A rms - 120
180 A rms - 180
225 A rms - 225
350 A rms - 350
500 A rms - 500
650 A rms - 650
800 A rms - 800
1000 A rms - 1000
1200 A rms
-
1200
N.O. Thermostat - NO
N.C. Thermostat - NC
RMS Current Limit/OC - CL
RMS Current Reg/OC - CR
Over Current Trip - OC
True Power Reg/CL – PR
Unbalance Alarm – UB
Shorted SCR Alarm - SF
Extended Ramp - ER
Lug Kit (>225 A) - LG
Can have multiple selections
4-20 mA - 01
0-10 Vdc - 02
0-5 Vdc - 03
Auto/Man - 04
Manual Pot input - 05
Others
-
xx

Description PF3 SCR Power Controller
4 Ametek HDR Power Systems Rev 3
Table 1.2 General Specifications of PF3 Models
Input line voltage: * 120, 240, 400, 480, or 575 Vac,
+10%, -15% , Three-phase
Line frequency: * 50 or 60 Hz
Current rating:
*
As indicated by model number (refer to Table 1.1)
Thermostat contact rating: 120 Vac, 5 A; resistive
Input Signal:
Non-isolated
Isolated
0 to 1.5 V (min); 0 to 10 V (max)
0 to 6 mA (min); 0 to 20 mA (max)
Control methods: 1. Potentiometer, 5 kΩ, 1/2 watt (Customer-supplied).
2. Dry contact closure (customer-supplied).
3. Temperature or process controller
*
*
Control signal input impedance:
Non-isolated input
Isolated input
1500 Ω
500 Ω
Control signal isolation:
From SCRs 2,500 Vac
From ac power input lines 2,500 Vac
From chassis 500 Vac
Power output:
Voltage regulation Voltage Squared
Power output linearity versus
control signals input
+2% (Non-isolated)
+5% (Isolated)
Power SCRs protection:
Current surge Subcycle I² T semiconductor fuse.
Transient voltage spikes (dv/dt)
SCCR Rating
Metal Oxide Varistor (MOV) and R-C snubber across each SCR pair; all
SCRs have PIV rating of 1,400 V.
100kA
Miscellaneous:
Phase-firing timebase 0 º to 180 º conduction per SCR
Controls: ZERO and SPAN potentiometers; 10-turn, screwdriver-adjustable.
Approvals UL/cUL (E151547), CE
Fan
-
cooling power (as applicable):
For 90 A through 225 A units 0.42 amperes, 50 VA (50 Hz)
0.38 amperes, 46 VA (60 Hz)
For 350 A through 500 A units 0.63 amperes, 76 VA (50 Hz)
0.57 amperes, 69 VA (60 Hz)
For 650 A through 1200 A units 4.2 amperes, 504 VA (50 Hz)
3.6 amperes, 432 VA (60 Hz)
Ambient Temperature range:
Environment 32 ºF to 122 ºF ( 0 ºC to 50 ºC) surrounding air
Pollution degree 2, Overvoltage Category III
Storage 14 ºF to 158 ºF ( -10 ºC to 70 ºC)
Weight per unit: Current Rating
60 through 225 A
350, 500 A
650 A
800, 1000, 1200 A
lbs
47
60
126
231
kg
18.2
27.3
57.3
105
Outline and mounting: See appropriate drawing in Appendix
* Specify with order
** If you will be using temperature/process controller, specify its output; e.g., 4-20 mA, 0-10 Vdc, 2-10 Vdc,
etc. with your order.
NOTE: The PF3 should be tested or operated with an adequate load since an open output will have line
voltage at the load connections.

PF3 SCR Power Controller Options
Rev 3 Ametek HDR Power Systems 5
CHAPTER 2 - Options
2.1 General
Several options are available from Ametek HDR Power Systems, and are described below. Most
options require current transformers (CTs), which are optional. On models rated from 60 through 225
amperes the CTs are mounted in the controller and on models rated from 350 amperes and higher, the
CTs are shipped separately.
2.2 Option OC (Three-Phase Overcurrent Trip)
The Three-Phase Overcurrent Trip Option (OC) provides circuit protection from output current
overloads by serving as a fast-gate shutdown. (Option OC functions similar to an electronic fuse.)
Trip point is adjustable from 30% to 200% of the SCR Power Control’s current transformer rating.
Current transformers on the SCR Power Control’s output lines allow Option OC to monitor
instantaneous peak current. When the peak current level exceeds the preset trip level, SCRs are
gated off, and the load current is shut down within 1/2 cycle. The TRIP RESET pushbutton must be
manually reset to resume operation.
Another feature of the overcurrent trip is an automatic reset. This is included with the current limit and
current regulation. Open the unit and locate the auto reset switch and reset pushbutton. With this
switch in the on position, the unit will continue to reset until the fault clears. If in the off position, the
unit will remain shut off until the reset PB is operated. The auto reset switch will always be in the off
position unless specified on the order.
The overcurrent trip option includes a Form C relay output and provisions for a remote overcurrent
reset push button. The relay output terminals are 39 and 40 for the N.C. and 40 and 41 for the N.O.
The remote reset terminals are 37 and 38. Reference Figure 5.1.
2.3 Option CL/OC (Current Limit/Overcurrent Trip)
The Three-Phase Current Limit Option (CL) prevents the output current of an SCR Power Control from
exceeding a preset maximum current level, as determined by the current limit control setting (30% to
125%). This option also includes an OC trip with Form C relay output contact and terminals for
connection of a remote OC reset pushbutton. The current limit adjustment is on the front of the unit,
while the overcurrent trip adjustment is located on the current regulation PCB on the inside of the unit.
A current transformer monitors the true RMS current, and feeds the information to Option CL, which
limits the true RMS current regardless of the process control signal. Current Limit is adjustable from
30% to 125% of the CT rating.
2.4 Option CR/OC (Current Regulation/Overcurrent Trip)
The Current Regulation option is much like the Current Limit. It includes an overcurrent trip feature, but
regulates the RMS current rather than limiting it. The adjustment range is 30 to 125% of the unit's
rating for the current regulation and 30 to 200% for the overcurrent trip. This option also includes an
OC trip with Form C relay output contact and terminals for connection of a remote OC reset
pushbutton. The current regulation adjustment is on the front of the unit, while the overcurrent trip
adjustment is located on the current regulation PCB on the inside of the unit.
The Three-Phase Current Regulation Option (CR) compares the feedback signal to the control signal,
so the line current will be linear to the control signal, and regulated to maintain a constant level at the
controller output despite load changed. Current regulation is adjustable from 30% to 125% of the CT
rating.

Options PF3 SCR Power Controller
6 Ametek HDR Power Systems Rev 3
2.5 Option PR (Power Regulation with Current Limit)
This option is for applications where it is desirable to regulate the true power instead of the RMS
current. This option also includes a RMS current limit as a safety feature. The Power Regulation
control is on the front of the unit while the Current Limit control is inside on the Power Regulation PCB.
The Three-Phase Power Regulation With Current Limit Option (PR), compares the feedback signal to
the control signal, so the output power will be linear to the control signal, and regulated to maintain a
constant power level at the controller output despite line and load changes. Current limit holds the
current to a preset maximum limit, and is adjustable from 30% to 125% of the full rated current
transformer rating.
2.6 Option ER (Extended Ramp)
The options limits the rate at which the output can increase to prevent high inrush currents with
transformer coupled loads or high cold-to-hot resistance ratios such as tungsten heating elements.
The rate of increase is limited to approximately 100% over four seconds. The standard extended ramp
time is 12 cycles.
2.7 Option LG (Lug Kit)
Option LG will provide compression lugs for the 350-1200 A Power Controllers.
2.8 Additional Options
The options described above are the ones most commonly used. Additional options are available. For
more information, contact Ametek HDR Power Systems.

PF3 SCR Power Controller Installation
Rev 3 Ametek HDR Power Systems 7
CHAPTER 3 - Installation
3.1 Mounting the PF3
Determine the voltage and current ratings from the nameplate of the unit (refer to Table 1.1). Then
determine space and mounting hole requirements by referring to the outline drawing (at the Appendix)
that applies to your model’s current rating. Mount the unit so the line and load connections are at the
top and ensure that upward airflow over the heat sink fins is unrestricted. On high current models,
allow adequate clearance for routing the relatively large diameter input and output lines.
3.2 Input/Output Wiring
Using appropriately sized and insulated conductors for the voltage and current ratings of your model,
make connections as shown in Figure 3.3. (Refer to Table 3.1 for wire size information). Torque
specifications of bolted connections can be found in Table 7.2.
A ground wire is required for proper operation. Use a 10 AWG or larger wire.
NOTICE
Use copper conductors rated 75 ºC minimum for all model current ratings.
The PF3 is phase-rotation insensitive. That is, three-phase input power can be
connected in any sequence to terminals L1, L2, and L3, and will not cause an out-of-
phase condition.
The fuses included are NOT meant for over current protection, separate branch circuit protection is
required.
On the “internal” side of the PF3, the wire from L2 should connect to the appropriate tap of transformer
T1 and T2, depending on the line voltage to be used. Check the T1 and T2 connection by opening the
PF3 cover; T1 and T2 terminal voltages are clearly marked. Reference Chapter 3.7.
Table 3.1 Wire Size Information
Model Size Wire/Cable
60 A 8 to 0 AWG
90 A 8 to 0 AWG
120 A 8 to 0 AWG
180 A 6 to 250 MCM
225 A 6 to 250 MCM
3.3 Fan Wiring (applicable to models rated 90 A and higher)
PF3 models rated 90 A and higher with cooling fans require 120 Vac power which must be supplied by
the customer. Fan power should be connected to terminals 21 and 22 as shown in Figure 3.1. Refer
to Table 1.2 for fan power requirements by model.
The PF3 terminals available for the 120 Vac fan connections are shown Figure 3.1 and in the
schematic in Appendix A. Optional 220 Vac fans are available.
WARNING
Branch circuit overcurrent protection required is to be provided in
accordance with the national and local codes of the inspecting authority.

Installation PF3 SCR Power Controller
8 Ametek HDR Power Systems Rev 3
3.4 Wiring Overtemperature Contacts
Normally-open (N.O.) heat sink thermostats are standard on all fan-cooled models (rated 90 A and
higher). These thermostats, which close on high heat sink temperature (200 ºF), may be used to
initiate an alarm, shunt trip, or other device for SCR protection. Thermostat connections are on
terminals 23 and 24 as shown in Figure 3.1.
If desired, normally-closed (N.C.) contacts may be substituted for the normally-open (standard). Heat
sink thermostats are optional on units with current ratings lower than 90 amperes and can be ordered
with either N.O. or N.C. contacts.
FAN POWER
120 Vac
(220 Vac
OPTIONAL)
OVER TEMP
N.O. STANDARD
(N.C. OPTIONAL)
21 22 23 24
Figure 3.1 Fan and Thermostat Connections
3.5 Command Signal Input
HDR’s Phase-Fired SCR Power Controllers have the capability of having either an isolated current or
non-isolated voltage Command Signal input. The standard input impedance is 500 ohms for isolated
and 1500 ohms for non-isolated.
All units are equipped with DIP switches, select “isolated” position for a 4-20 mA command signal and
“non-isolated” for a voltage input such as 0-10 V dc. See Figure 3.2.
The isolated input works best with an offset Command Signal such as 4-20 mA; however, it will work
with both offset and zero based Command Signals. Zero based Command Signals may have a small
amount of non-linearity (input to output) at the low end. This should not be a problem on closed loop
systems.
CAUTION
The application of fan power should precede, or coincide with, the turn-on of
the line voltage source that is to be controlled by the disconnect. How this is
accomplished and ensured is up to the customer.

PF3 SCR Power Controller Installation
Rev 3 Ametek HDR Power Systems 9
Current Input Voltage / Manual Pot Input
Figure 3.2 Isolated/Non-Isolated Switches
3.6 Determining Line Frequency
The PF3 is designed to operate on either 50 or 60 Hz. Usually the PF3 is shipped for 60 Hz operation,
unless otherwise ordered. The PF3 can be set for either ac line frequency by selecting 50 Hz or 60 Hz
on SW3 on the control board on the inside front door.
3.7 Voltage Changeover
On occasion, customers may wish to operate a PF3 SCR Power Controller on line voltages other than
what was specified when originally ordered. The PF3 may be changed to accept a wide range of line
voltages (120, 240, 400, 480, 575 Vac), so long as the load current does not exceed the PF3’s current
rating. This is accomplished by performing the procedure described below.
.
Using the system schematic (located in the Appendix) as reference, perform the voltage changeover
procedure as follows.
1. Open the SCR power controller, and locate transformer T1 and T2. The primary side of T1
transformer will contain two wires (one black, the other white and black), the primary side of T2 will
contain two wires (one red the other yellow). Refer to Figure 3.3.
T2 T1
Figure 3.3 T1, T2 Transformer Connections
WARNING
Voltage changeover should be performed by qualified personnel only.
Always remove power and properly lock out power to the unit before
attempting any service.
----OPEN ----
12 3 4C1
C2
NON-ISOLATED-C2
SW2
ISOLATED-C1
SW1

Installation PF3 SCR Power Controller
10 Ametek HDR Power Systems Rev 3
2. Unsolder the Black/White wire on T1 from the voltage tap, and resolder it to the tap desired, as
shown in Table 1. Unsolder the Yellow wire on T2 from the voltage tap, and resolder it to the tap
desired, as shown in Table below. Route the wires so that they are physically located under the
transformer terminals.
Table 3.2 Transformer Voltage Wiring
Desired Voltage T1 White &
Black Wire to
T2 Yellow
Wire to
120 120 120
208 240 240
220 240 240
240 240 240
380 400 400
400 400 400
415 400 400
480 480 480
575 575 575
3. Close the unit, and apply line power. The unit is now ready for operation on the line voltage
selected. It is a good idea to identify the unit with a label or tag, noting that PF3 has been
modified for line voltage other than what it was specified for. This may prevent accidental use on
an incorrect line voltage in the future.
3.8 Options
Options, if ordered by the customer, have been installed and set up at the factory. However, if the
current transformers (CTs) are shipped loose, they should be placed on the load lines when the load
lines are connected (first step in Chapter 3.2), and wired as indicated on the schematic in Appendix A.
On the PF3 Phase 1 CT connects to terminals 31 and 32; Phase 2 CT connects to terminals 33 and
34; and Phase 3 CT connects to terminals 35 and 36. Reference Figure 3.4 and schematic in
Appendix. If erratic control is noticed (power regulation only) reverse the current transformer
secondary connections.
Figure 3.4 Current Transformer Connections

PF3 SCR Power Controller Installation
Rev 3 Ametek HDR Power Systems 11
L3
L2
L1
X3
AC
INPUT
LINE X2
X1
LOAD
GROUND
CONTROL
Note: Unit shown with optional CT’s and CUR/PWR potentiometer.
Figure 3.5 Typical PF3 Line and Load Connections

Installation PF3 SCR Power Controller
12 Ametek HDR Power Systems Rev 3

PF3 SCR Power Controller Operation
Rev 3 Ametek HDR Power Systems 13
CHAPTER 4 - Operation
4.1 General
This Chapter provides information necessary for proper setup and operation of various methods used
to control the PF3.
a. Front Panel indications
b. Command input control
c. Remote manual control with a potentiometer
d. Auto/manual control with a controller and potentiometer
e. On/off control
f. Shutdown
Figure 4.1 Control Panel
4.2 Front Panel Indicators
Control Power Indicator – A Red Light Emitting Diode (LED) located on the front cover of the unit
signals when the control power is present.
Command Signal Indicator - The Command Signal Indicator is a green Light Emitting Diode (LED)
located on the front cover of the unit. The brilliance of this LED will change with a current Command
Signal. The brilliance increases with an increased Command Signal and decreases with a decreased
Command Signal. The LED will not function with a voltage or manual input.
Blown Fuse Indicator - The Blown Fuse Indicators are yellow Light Emitting Diodes (LED) located on
the front cover of the unit. There is one LED for each phase. Switches on each fuse controls the LED.
4.3 Command Input Control
The PF3 is calibrated at the Factory for the specified input type and normally does NOT need
adjustment. However, should a setup be required use the following methods. Refer to chapter 3.5 for
the Command signal input configuration.

Operation PF3 SCR Power Controller
14 Ametek HDR Power Systems Rev 3
a. If Option CR or PR is installed, set the 10-turn CUR/PWR potentiometer to its mid-point.
b. Set the ZERO and SPAN controls fully CCW (counterclockwise).
c. Connect a voltmeter across terminals X1 and X3 of the PF3. Set the voltmeter range to measure
full input voltage.
d. Close the fused disconnect or circuit breaker to apply power to the PF3. Turn the Process
controller on and set to demand zero power output.
Figure 4.2 Process Controller Input Connections
e. Adjust the ZERO control CW until the output just turns on, then turn the ZERO control CCW just to
the point where the output voltage reading is zero.
f. Set the Process controller to demand 100% output. Observing the voltmeter, adjust SPAN CW
just to the point where the reading is below the maximum output voltage. Then adjust SPAN CW
just to the point where the meter reading is at maximum.
g. Repeat steps 4.3e and 4.3f as necessary, to ensure proper control adjustments have been made.
h. Turn off the line power to the PF3 and disconnect the test equipment. The PF3 is now ready for
automatic operation.
i. If Option CR or PR is installed, adjust the CUR/PWR potentiometer CW until the output is limited
to the desired level.
4.4 Remote Manual Control with a Potentiometer
Some applications only require a manual control input and not a closed loop input from a process
controller. This potentiometer may be located on a remote panel near other controls related to the
process being powered by the PF3. It may be calibrated to correspond to a percentage of rated power
output, process temperature, or some other parameter. The potentiometer may by 500 Ω to 5 kΩ, and
should be rated at 1/2 watt, minimum.
a. With the power to the PF3 turned off, connect the potentiometer as shown in Figure 4.3. The CW
position is the full power output position. Terminal TB1-5 is internally connected to a positive dc
voltage source.
WARNING - ELECTRIC SHOCK CAN KILL
HAZARDOUS VOLTAGES exist at the output terminals and at the load when
the input voltage is connected. This condition exists even when the Controller is
set to deliver zero output. Always remove power and properly lock out power to
the unit before attempting any service, including the load.