Tweco 400 Ultra-Cut(May 2014) - Manual (Page 183)

ULTRA-CUT 100 XT/200 XT/300 XT/400 XT
Manual 0-5302 APPENDIX A-55
Other boards in the system include the System Bias Supply, the Relay & Interface PCB, Display PCB, Pilot PCB and AC Sup-
pression PCB. The CCM has 2 boards, the I/O (input/output) and the CPU (central processing unit) board. The CE units will also
have one or more EMI Filter boards on the input power.
System Bias supply PCB is powered from the 3 phase AC input and works from about 150V to over 600V covering all the normal
voltage ranges. It can operate from 2 phases (single phase) so it still provides bias power and can report a fault if a phase is
missing. The supply’s output is 24 VDC which powers the Relay board, the Display, the Pilot board and the 2 boards in the CCM.
System Bias also contains circuits to detect missing phase and determine if the AC voltage is within the correct range, not too
high or too low. It also signals to the CCM what voltage the unit is configured for. The System Bias supply PCB includes a relay,
K1, which only applies voltage to Auxiliary transformer, T1, primary when the input voltage is in the correct range.
The Relay and Interface PCB Accepts and distributed the output of the Aux Transformer. It has relay to control the pump, fans,
input contactors, the Arc Starter and the Inrush relays. A circuit on the Relay board accepts input from the Work current sensor,
HCT1, and Pilot current sensor (on the Pilot PCB) and sends the Enable signal to the Pilot boards IGBT switches via the J3 to J42
ribbon cable. Other inputs on the Relay board include those from the Negative Temperature Coefficient (NTC) ambient and cool-
ant temperature sensors. Coolant tank level switch and coolant flow switch, which determines if the flow is above the required
minimum rate, also send signals to the Relay Board. Ultra-Cut units include a flow sensor whose output to the Relay Board is
a series of pulses whose frequency indicates the flow rate and can detect the presence of gas bubbles in the coolant. All these
signals pass to the CCM via a 40 conductor ribbon cable going to the CCM I/O board.
The Display Board Has LEDs for AC, TEMP, GAS & DC. It also has a 4 digit 7 segment display for status and fault information.
AC LED indicates the input contactors to the inverters have been commanded to close, but does not mean they are closed. TEMP
means one or more inverters or the coolant has exceeded the allowed temperature. GAS means gas is flowing and coolant flow
is OK. DC means the inverters output voltage is above 60 VDC.
The first digit of the 7 segment display shows the letter, “C”; “E”; “L” or is blank. During the initial power up sequence the letter
“C” followed by the other 3 digits, indicates the CCM code revision. Status or Fault codes which may occur during the power up
sequence or any time thereafter are preceded by letters “E” for an active fault or “L” for a “latched” or “last” fault that stopped
the process but is no longer active. When there is no Fault or active Status code, the output current setting is displayed with the
first digit blank. If the system is an Ultra-Cut XT using the Auto Gas Control, DFC 3000, the display will show “0” until a process
has been loaded. If there is a fault or other status showing the display will alternate between the current setting and the fault.
The Pilot PCB contains a pair of parallel IGBT transistors working as an electronic switch to connect and disconnect the torch tip
from the 1st inverter section.
When the pilot electronic switch is closed and the pilot is ignited by the Arc Starter, current from the 1st section flows between
electrode and tip. Then as transfer begins, a small current from the 2nd inverter flows from electrode to work. When transfer is
detected the pilot switch is opened and current from the 1st section is free to flow to the work through the diode which is also
on the Pilot board. The Pilot PCB also contains a pilot current sensor to detect and measure the level of pilot current. Additional
resistor/capacitor (RC) circuits on the pilot PCB assist and stabilize the pilot and transferred arcs.
Art # 12301
The AC Suppression PCB has capacitors and other transient suppression components to protect the system from transients on
the AC lines. It also provides power for the neon AC present indicators which illuminate when AC power is connected even with
ON-OFF switch, CB1, off.