Other Considerations - TTI PL-P Serie Manuel D'utilisation

Protection
Over-voltage protection is fitted to this supply and will be triggered if the voltage across the output
terminals exceeds 7 Volts. If this occurs the power supply output is crowbared by a thyristor; the
power supply will then shut down and TRIP will be shown in the display. The power supply can be
reset by turning off the DC output switch or by turning the supply off.
The power supply is protected from reverse voltages by a diode; the reverse current must not
exceed 3 Amps.
General
Connection to the Load
The load should be connected to the positive (red) and negative (black) terminals marked
OUTPUT. Both are fully floating and either can be connected to ground. The negative terminals
are permanently connected to the power supply output, whilst the positive ones are switched
electromechanically (main outputs) or electronically (logic outputs). The green terminal is
connected to chassis and to the earth (ground) of the AC input cable.
If the unit is to be used with live measuring or load circuits which have protective earth terminals,
ensure that all protective earth terminals are connected to a protective conductor prior to
switching on (the green front panel terminal may be used for this purpose).
If the unit is to be used with live measuring or load circuits which do not have protective earth
terminals, ensure that the unit AC line plug is inserted before making connections between the
unit output terminals and such circuits.
Remote Sensing
The unit has a very low output impedance, but this is inevitably increased by the resistance of the
connecting leads. At high currents, this can result in significant differences between the indicated
source voltage and the actual load voltage, (two 50mΩ connecting leads will drop 0·2V at 2
Amps, for instance). This problem can be minimised by using short, thick, connecting leads, but
where necessary it can be completely overcome by using the remote sense facility.
This requires the sense terminals to be connected to the output at the load instead of at the
source; remove the two shorting bars and connect the sense terminals directly to the load. To
avoid instability and transient response problems, care must be taken to ensure good coupling
between each output and sense lead. This can be done either by twisting the leads together or by
using coaxially screened cable (sense through the inner). An electrolytic capacitor directly across
the load connection point may also be beneficial.
The voltage drop in each output lead must not exceed 0·5 Volts.
The shorting bars must be re-fitted if the remote sensing facility is not being used. Remote
sensing cannot be used in the tracking or series modes on either output.

Other Considerations

The power supplies generate considerable heat and require a full air cooling flow for correct
operation. Do not obstruct any of the cooling slots in the cover, or block the inflow of air at the
bottom.
Avoid allowing the supply to get damp, and keep away from corrosive fluids.
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