Transcript No Slide Title

Power Supply Control
Feedback Control
Power Supply Control
Lesson Objectives
When you finish this lesson you will
understand:
• Secondary Current Control
• Phase Shift Heat Control
• Spot Weld Quality Testing
• Equipment Monitoring
• Feedback Control
Learning Activities
1. View Slides;
2. Read Notes,
3. Listen to lecture
4. View Demo
5. Do on-line
workbook
6. Do Homework
Keywords: Transformer, Tap Setting, Primary Current, Secondary
Current, Silicon Controlled Rectifier, Electrode Force, Power
Factor, Toroid, Hall Effect Transducer, Linear Voltage Differential
Transformer, Dynamic Resistance
Block Diagram of Single-Phase
Spot Welder
Contactor
Main Power Line
Spot Weld
Transformer Tap Switch
Es
Vp
Parallel/Series
Tap Switches
E
E
s
(a) Parallel
S2
P2
S1
P1
Es
S1
P1
s
Vp
(b) Series
S2
P2
Es
Vp
N=np/ns
Vs= Vp/N
Is = Ip N
60 Cycle
AC
Rules for SCR Conduction
• can conduct when anode is + with respect to cathode
• once initiated, can only be stopped by removal of anode voltage
• initiated by a pulse on ignitor
Phase Shift Heat Control
(a) Current Controlled by Tape Settings
(b) Current Controlled by Phase Shift Setting
Link to:
Phase Shift Heat Control Demo
60 Cycle
AC
Electrode
Force Gage
Electrode
Equipment Arrangement
Power
Supply
Strain Gage
Signal Conditioner
Oscilloscope
Voltage
Leads
Print
Displacement Transducer
Isolation
Box
Tap
Integration
Data
Recorder