Chapter 5—System Configuration and Operation
Power Xpert C445 Global Motor Management Relay
MN042003EN—January 2019
www.eaton.com
89
Auto Transformer Operation Mode
The auto transformer reduced voltage motor starter profile
accepts start/stop commands to control motors wired in a
reduced voltage auto transformer configuration. When a start
command is received Output 3(star) will be activated. Then
after the Network Contactor Delay time expires, Output
1(start) activates starting the motor with the reduced voltage
from the auto transformer. When the C445 detects the
motor is up to speed or the Maximum Star Winding Time
expires, whichever occurs first, the Network Contactor Delay
timer is started and Output 3 is de-activated. After the
Network Contactor Delay time expires, Output 2(run) also
activates, which transitions the transformer to full voltage.
After a second Network Contactor Delay time expires,
Output 1(start) de-activates placing the control into full
voltage run mode.
The C445 will issue a control fault when:
●
A Run1 command is active and phase voltage is present
and no phase current is detected after the Control
Switching Time expires.
●
A Stop command is active and current is detected after the
Control Switching Time expires.
Outputs 1, 2 and 3 will be de-activated anytime the C445
experiences a fault/inhibit condition.
●
Output 1 – auto transformer reduced voltage starter
START coil (NO)
●
Output 2 – auto transformer reduced voltage starter RUN
coil (NO)
●
Output 3 – auto transformer reduced voltage starter STAR
coil (NO)
Figure 88. Timing Diagram for the Auto Transformer
Operation Mode
Recommended User Interface Options for the
Auto Transformer Operation Mode
Figure 89. C445UM: Monitoring User Interface
The Monitoring User Interface can be used with any
operation mode. If selected as a local control source, the
User Interface Start and Stop buttons are enabled in Auto
Transformer Mode. Users may optionally disable local start
or reset functionality if desired.
C445UM may still be used in Auto Transformer if the User
Interface is not the local control source. Start, Stop and Auto
buttons will be disabled. If pressed, the screen will notify the
user that this functionality is not enabled. Control Status
LEDs indicating running, stopped and Auto status will still
function.
STAR
START
Timing Diagram
RUN
Settle Time
Max star time
Settle Time
Control Fault Delay
Control Fault Delay
