ENTRON Controls, LLC. • 700120S • Page 27
3.9 COOLING REQUIREMENTS FOR CONTACTORS
SOLID STATE MANUFACTURER’S COOLING RECOMMENDATIONS
600 A – SCR Solid State Contactor – NO LONGER AVAILABLE
1200 A – SCR Solid State Contactor
1800/2200/3200 A – SCR Solid State Contactor
1 GPM at 104°F (40°C) maximum inlet temperature.
Be sure power to an electronic contactor is turned off when water is turned off.
With a voltage applied, most water will ionize and begin to conduct current between points of
high differential voltages. This current is sufficient to heat the water past the boiling point,
creating steam and possibly causing the rubber hose to burst. The water spraying over the high
voltage circuit can cause considerable damage to the contactor and, most likely, the control
circuitry as well. Never use metallic or other conductive tubing to plumb a water-cooled resistance
welding contactor. Heater hose has a very high carbon content and should not be used for
contactor plumbing. A low carbon, reinforced hose (such as the hose originally supplied with
the unit), no less than 18" long, must be used to connect the Heatsinks to each other and to the
bulkhead fitting on the inside wall of the cabinet (see plumbing instructions on Wiring Diagram).
The 1200A modular water-cooled SCR Contactor is electrically isolated from electrical circuit
within the contactor section. No minimum length of water hose is required for electrical isolation
of the contactor. It is still recommended to turn power off when control is not in use.
WATER OFF – POWER OFF
POWER ON – WATER ON
For all water-cooled Heatsinks, be sure water is turned ON before placing welder in operation.
An open drain is recommended for best operation. If a closed return system is used, be sure
return line is properly sized so that back pressure will not reduce water flow below
recommendations. A sight flow indicator is recommended.
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