40
83503001 Rev G
3.9.4. Noise and Impedance Effects
To minimize the noise pickup or radiation, the load wires and remote sense wires
should be twisted pairs to the shortest possible length. Shielding of sense leads may be
necessary in high noise environments. Where shielding is used, connect the shield to
the chassis via a rear panel Ground screw. Even if noise is not a concern, the load and
remote sense wires should be twisted-pairs to reduce coupling, which might impact the
stability of the power supply. The sense leads should be separated from the power
leads.
Twisting the load wires reduces the parasitic inductance of the cable, which could
produce high frequency voltage spikes at the load and the output of the power supply,
because of current variation in the load itself.
The impedance introduced between the power supply output and the load could make
the ripple and noise at the load worse than the noise at the power supply rear panel
output. Additional filtering with bypass capacitors at the load terminals may be required
to bypass the high frequency load current.
3.9.5. Inductive Loads
Inductive loads can produce voltage spikes that may be harmful to the power supply. A
diode should be connected across the output. The diode voltage and current rating
should be greater than the power supply maximum output voltage and current rating.
Connect the cathode to the positive output and the anode to the negative output of the
power supply.
Where positive load transients such as back EMF from a motor may occur, connect a
surge suppressor across the output to protect the power supply. The breakdown
voltage rating of the suppressor must be approximately 10% higher than the maximum
output voltage of the power supply.
3.9.6. Making the Load Connections
WARNING
Hazardous voltages may exist at the outputs and the load connections
when using a power supply with a rated output greater than 40V. To
protect personnel against accidental contact with hazardous voltages,
ensure that the load and its connections have no accessible live parts.
Ensure that the load wiring insulation rating is greater than or equal to the
maximum output voltage of the power supply.
CAUTION
Ensure that the load wiring mounting hardware does not short the output terminals.
Heavy connecting cables must have some form of strain relief to prevent loosening the
connections or bending the bus-bars
8V to 100V Models
Refer to Fig.3-6 for connection of the load wires to the power supply bus-bars and to
Fig.3-7 for mounting the bus-bars shield to the chassis.
