3.5. DC Output Connection
Warning
SHOCK HAZARD. Turn off AC power before making any rear panel connections. Ensure that MagnaDC power supply connections, load wiring, and load connections are either insulated or covered so that no accidental contact with lethal output voltages can occur.
The DC output connection method for the XR Series MagnaDC power supply depends on the model’s rated output voltage. Models rated 1000 Vdc and below connect to the load through output bus bars on the rear panel, models rated 1250 Vdc to 3000 Vdc connect through positive and negative output studs, and models rated above 3000 Vdc connect through a coaxial high voltage output receptacle.
3.5.1. Models 1000 Vdc and Below
The DC output of the XR Series MagnaDC power supply connects to the DC bus by attaching two cables to the output bus bars (0.250 x 1.000 inch tin plated copper). Magna-Power recommends DC power cables be crimped to ring terminals and securely fastened to the bus bars using the included 3/8” bolts, washers, and lock washers. The bus bars contain 3/8”-16 threaded inserts. The recommended torque for the DC connection is 15 lb-ft (20.3 Nm).
Caution
Make sure connections are tight to avoid overheating of the bus bars.
After connections are made, screw the four standoffs into the back panel and place the protective metal cover over the connections, as described in Protective Cover.
Select a wire size sufficient to handle the maximum output current of the unit, no matter what the intended load current or current limit setting.
The recommended wire size for different current levels are shown in the table below.
Wire Size (USA) |
Equivalent Wire Size
(International)
|
Wires Per Output Terminal |
Maximum Current |
|---|---|---|---|
6 AWG |
10 mm2 |
1 |
85 Adc |
4 AWG |
25 mm2 |
1 |
110 Adc |
3 AWG |
25 mm2 |
1 |
130 Adc |
2 AWG |
35 mm2 |
1 |
150 Adc |
1 AWG |
50 mm2 |
1 |
170 Adc |
1/0 AWG |
50 mm2 |
1 |
200 Adc |
2/0 AWG |
70 mm2 |
1 |
235 Adc |
3/0 AWG |
95 mm2 |
1 |
275 Adc |
4/0 AWG |
120 mm2 |
1 |
315 Adc |
1/0 AWG |
50 mm2 |
2 |
400 Adc |
2/0 AWG |
70 mm2 |
2 |
470 Adc |
3/0 AWG |
95 mm2 |
2 |
550 Adc |
4/0 AWG |
120 mm2 |
2 |
630 Adc |
1/0 AWG |
50 mm2 |
4 |
800 Adc |
2/0 AWG |
70 mm2 |
4 |
940 Adc |
3/0 AWG |
95 mm2 |
4 |
1100 Adc |
4/0 AWG |
120 mm2 |
4 |
1260 Adc |
Notes:
Capacity for AWG wires derived from the National Electric Code. Maximum ambient temperature: 40°C. Maximum wire temperature: 90°C. Continuous duty with wires in free air, not bundled or in conduit.
Capacity of aluminum wire is approximately 84% of the capacity listed for copper wire.
For higher current levels, it’s recommended to use bus bars with holes for additional cable feeds or direct bus bar connection to the load.
Warning
FIRE HAZARD. Select a wire size large enough to carry the XR Series MagnaDC power supply model’s maximum rated current to prevent overheating of the wires. Make sure power cable connections are secured tightly in accordance with the torque recommendation to prevent overheating of the bus bars.
3.5.2. Models 1250 Vdc to 3000 Vdc
The DC output of XR Series MagnaDC power supply models rated 1250 Vdc to 3000 Vdc connects to the load by attaching two cables to the positive and negative output studs on the rear panel. Magna-Power recommends DC power cables be crimped to ring terminals and securely fastened to the output studs using the two (2) 1/4-20 bolts. The recommended torque for the DC connection is 5 lb-ft (6.8 Nm).
Caution
Make sure connections are tight to avoid overheating of the output connections.
After connections are made, screw the four standoffs into the back panel and place the protective metal cover over the connections, as described in Protective Cover.
3.5.3. Models Above 3000 Vdc
The DC output of XR Series MagnaDC power supply models rated above 3000 Vdc connects to the load using the provided high voltage coaxial output cable (RG-8/U), available in 24 in, 36 in, and 60 in lengths. Connect the output cable to the power supply’s 83-1R output receptacle and secure it with the screw lock, threading the PL-259 connector’s coupling ring clockwise onto the receptacle until hand-tight. The other end of the cable should be securely fastened to the load. After connections are made, screw the four standoffs into the back panel and place the protective metal cover over the connections, as described in Protective Cover.
3.5.4. Grounding the DC Output
For models rated 1000 Vdc and below, the output of the XR Series MagnaDC power supply is floating up to the DC output isolation specifications. A floating output means the output terminals are not connected electrically to ground and the produced output voltage is from the positive terminal with respect to the negative terminal. Neither output terminal needs to be connected to ground, however if desired, either the positive or negative terminal can be connected to earth ground. The maximum output voltage to ground is ±1000 Vdc.
For models rated above 1000 Vdc and up to 3000 Vdc, the output is floating up to ±(1500 Vdc + Vo/2) maximum output voltage to ground, where Vo is the model’s maximum rated voltage.
For models rated above 3000 Vdc, the output is not isolated; the output polarity of the single output connection with respect to ground — positive (POS) or negative (NEG) — must be specified at time of order, designated in the model number. For these models, series operation can only be achieved by connecting a positively grounded supply to a negatively grounded supply, providing a plus and minus configured series system.