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CABLE INDUCTANCE, AND ITS EFFECTS ON WELDING
Excessive cable inductance will cause the welding performance to degrade. There are several factors that contribute to the overall inductance of the cabling system including cable size, and loop area. The loop area is defined by the separation distance between the electrode and work cables, and the overall welding loop length. The welding loop length is defined as the total of length of the electrode cable (A) + work cable
(B)+ work path (C) (see Figure A.1 below). To mini- mize inductance always use the appropriate size cables, and whenever possible, run the electrode and work cables in close proximity to one another to mini- mize the loop area. Since the most significant factor in cable inductance is the welding loop length, avoid excessive lengths and do not coil excess cable. For long work piece lengths, a sliding ground should be considered to keep the total welding loop length as short as possible.
FIGURE A.2
POWER | A |
WAVE |
C |
WORK
B
REMOTE SENSE LEAD CONNECTIONS
Voltage Sensing Overview
The best arc performance occurs when the Power Wave AC/DC 1000 has accurate data about the arc conditions. Depending upon the process, inductance within the electrode and work cables can influence the voltage apparent at the studs of the welder, and have a dramatic effect on performance. To counteract this negative effect, remote voltage sense leads are used to improve the accuracy of the arc voltage information supplied to the control pc board.
There are several different sense lead configurations that can be used depending on the application. In extremely sensitive applications it may be necessary to route cables that contain the sense leads away from the electrode and work welding cables.
CAUTION
If the remote voltage sensing is enabled but the sense leads are missing, improperly connected, or if the electrode polarity switch is improperly con- figured extremely high welding outputs may occur.
Electrode Voltage Sensing
The remote ELECTRODE sense lead (67) is built into the wire feeder control cable (K1785) and accessible at the wire drive. It should always connected to the wire drive feed plate when a wire feeder is present. Enabling or disabling electrode voltage sensing is application specific, and automatically configured through software.
Work Voltage Sensing
For most applications the use of a remote work volt- age sense lead is recommended. The Power Wave AC/DC 1000 is shipped from the factory with the remote work voltage sense lead enabled. It must be attached to the work as close to the weld as practical, but out of the weld current path. For more information regarding the placement of remote work voltage sense leads, see the section entitled "Voltage Sensing Considerations for Multiple Arc Systems." The remote WORK sense lead (21) can be accessed at one of two locations. Either at the wire drive via the wire feeder control cable (K1785), or at the
CAUTION
Never connect the WORK sense lead at two differ- ent locations.
WARNING
ELECTRIC SHOCK can kill.
•Do not touch electrically live parts or electrodes with your skin or wet clothing.
•Insulate yourself from the work and ground.
•Always wear dry insulating gloves.
Some simplified applications may perform adequately by sensing the work voltage directly at the WORK STUD without the use of a remote work voltage sense lead. If a remote work voltage sense lead is not used, it must be disabled as follows:
1. Turn off power to the power source at the dis- connect switch.
2. Remove the front cover from the power source.
POWER WAVE® AC/DC 1000