Ametek RF3 SCR Series Operation and maintenance manual

SCR POWER CONTROLLER
Instruction, Operation and
Maintenance Manual
Number: 9100047
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 r p ow e r. c o m
RF3 SCR Series
30-1200 Amperes
Three-phase
Phase-fired

This manual applies to all Model RF3 SCR Power Controls. Former RF3 manual – 9100018 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 April 2015 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.

RF3 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 Selecting the Proper Rated Power Controller 4
1.5 Specification 4
1.6 Option LG (Lug Kit) 4
1.7 Additional Options 4
CHAPTER 2 - INSTALLATION ............................................................................................................................ 7
2.1 Mounting the RF3 7
2.2 Input/Output Wiring 7
2.3 Fan Wiring (applicable to models rated 90 A and higher) 7
2.4 Wiring Overtemperature Contacts 8
2.5 Command Signal Input 8
2.6 Determining Line Frequency 9
2.7 Voltage Changeover 9
CHAPTER 3 - OPERATION ............................................................................................................................... 11
3.1 General 11
3.2 Front Panel Indicators 11
3.3 Command Input Control 11
3.4 Remote Manual Control with a Potentiometer 12
3.5 Auto/Manual Control with a Controller and Remote Potentiometer 13
3.6 On/Off Control 14
3.7 Shutdown 14
3.8 Overcurrent Trip 15
CHAPTER 4 - THEORY...................................................................................................................................... 17
4.1 Functional Description 17
4.2 Overview of the RF3 17
4.3 Digital Firing Control Circuit 17
4.4 Pulse-Train Firing 17
4.5 Phase-Lock Loop 17
4.6 SPAN and ZERO Controls 18
4.7 Voltage-Squared Feedback 18
4.8 Shut-down 18
4.9 Soft-Start Circuit 18
CHAPTER 5 – TROUBLESHOOTING ............................................................................................................... 19
5.1 Customer-Service Program 19
5.2 Troubleshooting Typical Symptoms 19
5.3 Static Precautions when Servicing 19
5.4 Environmental Problems 20
5.5 Input Power and Load Connections 20
5.6 Correcting Troubles in the RF3 Itself 21
CHAPTER 6 - SERVICE ..................................................................................................................................... 23
6.1 Communication Procedures 23
6.2 Spare Parts Orders – Routine or Emergency 23
6.3 Spare Parts List 24

Table of Contents RF3 SCR Power Controller
ii Ametek HDR Power Systems Rev 3
6.4 Drawing List 25
CHAPTER 7 – WARRANTY POLICY ................................................................................................................ 26
7.1 Warranty 26
7.2 In-house Repair Services 26
APPENDIX .......................................................................................................................................................... 28
Appendix A – System Schematic 28
Appendix B – 30-225 A Outline 29
Appendix C – 350-500 A Outline 30
Appendix D – 650 A Outline 31
Appendix E – 800-1200 A Outline 32

RF3 SCR Power Controller Table of Contents
Rev 3 Ametek HDR Power Systems iii
TABLE OF CONTENTS
Par. Title Page
ILLUSTRATIONS
Figure 2.1 Fan and Thermostat Connections .................................................................................................. 8
Figure 2.2 Isolated/Non-Isolated Switches ...................................................................................................... 9
Figure 2.3 T1, T2 Transformer Connections ................................................................................................... 9
Figure 3.1 Control Panel .................................................................................................................................. 11
Figure 3.2 Process Controller Input Connections ........................................................................................ 12
Figure 3.3 Remote Control with a Potentiometer ......................................................................................... 12
Figure 3.4 Auto/Man Control with Controller and Remote Potentiometer ................................................. 13
Figure 3.5 On/Off Control ................................................................................................................................ 14
Figure 3.6 Shutdown Control .......................................................................................................................... 14
Figure 3.7 Current Limit/Trip Board ............................................................................................................... 15
Figure 4.1 AC Switch and SCR On-time ......................................................................................................... 17
TABLES
Table 1.1 kVA vs. Leakage Impedance ............................................................................................................ 4
Table 1.2 RF3 Model Number Breakdown ....................................................................................................... 4
Table 1.3 General Specifications of RF3 Models ............................................................................................ 5
Table 2.1 Wire Size Information ........................................................................................................................ 7
Table 2.2 Transformer Voltage Wiring ........................................................................................................... 10
Table 5.1 Troubleshooting Chart (Symptoms and Solutions) ..................................................................... 21
Table 5.2 Torque Specifications ..................................................................................................................... 21
Table 6.1 RF3 Spare Parts List ....................................................................................................................... 24
Table 6.2 RF3 Drawing List ............................................................................................................................. 25

Table of Contents RF3 SCR Power Controller
iv Ametek HDR Power Systems Rev 3

RF3 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 5) 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.

Safety Instructions RF3 SCR Power Controller
2 Ametek HDR Power Systems Rev 3

RF3 SCR Power Controller Description
Rev 3 Ametek HDR Power Systems 3
CHAPTER 1 - Description
1.1 General Description
The RF3 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
RF3’s output voltage is proportional to its input signal. The RF3 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 RF3 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.
The Three-Phase Overcurrent Trip is included and provides circuit protection from output current
overloads by serving as a fast-gate shutdown. (similar to an electronic fuse.) Trip point is adjustable
from 30% to 200% of the SCR Power Control’s current transformer rating. 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.
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 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 3.7.

Description RF3 SCR Power Controller
4 Ametek HDR Power Systems Rev 3
1.4 Selecting the Proper Rated Power Controller
Use the Table below to select the proper sized RF3. You will need the incoming line voltage and the
transformer leakage impedance. For voltages other than 480V, ratio the incoming voltage using the
480V chart provided below. For example, a 240V system the kVA would be half that on the chart for
any given kVA. The kVA is based upon the one cycle surge ratings of the SCRs installed in each of
the power controls.
Table 1.1 kVA vs. Impedance
Impedance
4% 6% 8% 10% 12%
Current Rating kVA
60 Amps 18 26 35 44 50
120 Amps 35 53 70 87 100
180 Amps 48 74 100 130 150
225 Amps 65 110 150 190 190
350 Amps 82 123 163 204 246
500 Amps 132 198 265 331 400
800 Amps 240 359 480 600 665
1200 Amps 499 747 998 998 998
1.5 Specification
Specifications for the RF3 SCR power controller are given in Tables 1.1 and 1.2.
Table 1.2 RF3 Model Number Breakdown
RF3 – 480 – 225 – NO – LG – 01
NOTE: N.O. Thermostat is included in current ratings above 60 A.
1.6 Option LG (Lug Kit)
Option LG will provide compression lugs for the 350-1200 A Power Controllers.
1.7 Additional Options
The options described above are the ones most commonly used. Additional options are available. For
more information, contact Ametek HDR Power Systems.
120 Vac - 120
240 Vac - 240
400 Vac - 400
480 Vac - 480
575 Vac -
575
30 A rms - 30
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
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