Thermal Dynamics iCNC Performance, Service And Installation Manual

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iCNC Perfromance
Manual 0-5401 SPECIFICATIONS 2-5
4. Assemble the transformer and power resistor in a metal box. Connect a 3 wire (w/gnd) power cord with ground wire
attached to the metal box for safety. If a plastic box is used instead, connect the transformer core and the resistor
mounts to the power cord ground wire. There should be a fuse ¼ - ½ A, in series with the transformer primary. From
the transformer secondary connect one wire to the utility safety ground. This could be the cutting table frame, the
ground terminal of the 120 or 220 VAC outlet or the test box if grounded as indicated.
An excellent ground measures 1 ohm or less. Up to 3 ohms is often acceptable, higher reduces the effectiveness of the
EMI suppression.
0.1 VAC = 1 OHM,
0.3 VAC = 3 OHM,
etc.
Triad N-68X
Utility (building) GND
11
5 V
AC
220 VAC
GND
Triad N-68X
F
F
11
5 V
AC
11
5 V
AC
11
5 V
AC
11
5 V
AC
GND
120 VAC
R = 1.2K, 15W
(2.2K, 25W for 220 VAC)
Ground Rod with other
connec
ti ons removed
Art # A-12710
5. Increasing the ground rod length beyond 20 - 30 ft (6.1 – 9.1 m) does not generally increase the effectiveness of the
ground rod. A larger diameter rod which has more surface area may help. Sometimes keeping the soil around the ground
rod moist by continuously running a small amount of water into it will work. Adding salt to the soil by soaking it in salt
water may also reduce its resistance. You may also try a chemical ground rod devise. When these methods are used,
periodic checking of the ground resistance is required to make sure the ground is still good.