Phase Control
7.11 Phase Control
When the Starter Type parameter is set to Phase Control, the MX
2
is configured to operate as a phase controller or voltage follower.
This is an open loop control mode. When a start command is given, the RUN programmed relays energize. The firing angles of the
SCRs are directly controlled based on voltage or current applied to the Analog Input.
Phase control can be used to directly control the voltage applied to motors, resistive heaters, etc. When in Phase Control mode, the phase
angle of the SCRs, and hence the voltage applied, is directly controlled based on the analog input signal. The MX
2
reference command
can be generated from any 0-10V, 0-20mA or similar source, such as a potentiometer, another MX
2
or an external controller such as a
PLC.
A reference input value of 0% results in no output. A reference input value of 100% results in full (100%) output voltage. The actual
input voltage / current that results in a given output can be adjusted through the use of the Analog Input Offset and the Analog Input
Span parameters.
z NOTE: The power stack must be rated for continuous non-bypassed duty in order to operate in Phase Control mode
continuously, NO BYPASS.
z NOTE: When operating in Phase Control mode, the acceleration ramp, kick, and deceleration settings have no effect
on operation.
z NOTE: When in Phase Control mode the following motor / starter protective functions are available:
• Current Imbalance Residual Ground Fault
• Over Current Instantaneous Over Current (IOC)
• Current while Stopped Phase Rotation
• Under Current Phase Loss
• Over Voltage Under Frequency
• Under Voltage Over Frequency
• Motor OL
165
7 - THEORY OF OPERATION
Output Voltage vs Analog Input
0
10
20
30
40
50
60
70
80
90
100
0 10 20 30 40 50 60 70 80 90 100
Analog Input (%)
Output Voltage (%)
Figure 45: Phase Control Mode
To Next Page
Loading...
Need help?
General
