Tweco 15XC Merlin - Manual (Page 22)

INTRODUCTION & DESCRIPTION 2-8 Manual 0-2251
2.5 THEORY OF OPERATION (continued)
The system has several built-in interlocks to provide safe
and efficient operation. When an interlock shuts down the
system, the torch switch (or control device) must be used
to restart the system.
The torch has a built-in parts-in-place interlock that pre-
vents accidental torch starting when torch parts are not
properly installed. A flow switch on the coolant return
lead detects reduced coolant flow caused by improper
torch assembly. If not satisfied, the switch interrupts
power to the tip and electrode.
Pressure switches act as an interlock for the gas supplies. If
supply pressure falls below minimum requirements the
pressure switches will open, shutting off the power to the
contactors, and the GAS indicator will go out. When
adequate supply pressure is available the pressure
switches close, allowing power to be resumed for cutting.
Thermal overload sensors are located in the transformer
and main heatsink in the power supply. If one of these
components is overheated the appropriate switch will
open up, causing the temperature light to turn from green
to red and shutting off power to the main contactor. When
the overheated component cools down the switch will
close again and allow operation of the system.
Interlocks
Parts-In-Place Interlock
Gas Pressure Interlock
Thermal Interlock