Lincoln Electric IM481-B manual Machine & Circuit Protection Thermal Protection Light, Paralleling

PARALLELING

There are no provisions on the CV 500-I to permit par- alleling.

DIODE OPTION (Factory installed only)

The CV 500-I Diode option is required to utilize the cold start and cold electrode sensing features of the NA-3, NA-5 or NA-5R. When this option is not used with an NA-3, NA-5 or NA-5R, see the CV 500-I / NA-3, CV 500-I / NA-5 or CV 500-I / NA-5R connection diagram for instructions on how to disable this circuit. If the circuit is not disabled, the wire cannot be inched down.

METER OPTION

Factory installed Ammeter and Voltmeter

Machine & Circuit Protection (Thermal Protection Light)

The power source is thermostatically protected with proximity thermostats against overload or insufficient cooling. One thermostat is located on the nose of the center bottom primary coil and a second thermostat is attached to the lead connecting the secondaries. Both thermostats are connected in a series with the 2- 4 circuit. If the machine is overloaded, the primary thermostat will open, the output will be zero, and the thermal protection light will be on; the fan will continue to run. The secondary thermostat will open either with an excessive overload or insufficient cooling. The out- put will be zero and the protection light will be on; the fan will continue to run. When the thermostats reset the protection light will be off.

The power source is also protected against overloads on the SCR bridge assembly through an electronic protection circuit. This circuit senses an overload on the power source and limits the output to 550 amps by phasing back the SCR’s.

Protection is provided to protect the circuitry from accidental grounds. If the customer accidentally “grounds” 75, 76, or 77 to the positive output lead, the output will be reduced to a low value, thus preventing any damage to the machine. If the ground occurs between 75, 76, 77 and the negative output lead, one of the PC board “self-restoring” fuses will blow, pre- venting any machine damage. After the ground is cleared, the fuses automatically reset within a few seconds.

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