WARNING!
Such voltages are exceedingly hazardous and great care should be taken to shield
the output terminals for such use. On no account should the output terminals be touched when
the unit is switched on under such use. All connections to the terminals must be made with the
power switched off on all units.
It should be noted that the unit can only source current and cannot sink it, thus units cannot be
series connected in anti-phase.
The unit can be connected in parallel with others to produce higher currents.Where several units
are connected in parallel, the output voltage will be equal to that of the unit with the highest output
voltage setting until the current drawn exceeds its current limit setting, upon which the output will
fall to that of the next highest setting, and so on. In constant current mode, units can be
connected in parallel to provide a current equal to the sum of the current limit settings.
Application of an external voltage source to the output
In common with all series regulated single-ended power supplies, the unit is not capable of
sinking current provided from an external source.
If a voltage greater than the set output voltage of the unit is applied from an external source, the
internal regulator will turn off, no current will flow, and the voltage meter will read the applied
voltage. No damage will result providing the applied voltage does not exceed the maximum
output voltage of the power supply by more than 20 Volts. Application of a voltage greater than
this is prohibited.
If a reverse voltage is applied, this will be clamped by an internal reverse protection diode. The
reverse current should not exceed 3 Amp.
Additional Instructions for Quad Mode Dual Versions
Quad-Mode Dual versions of the power supplies incorporate a bank of four interlocked push-
button switches which enable any one of four different modes of operation to be selected. These
are as follows:
1. Isolated
Each power supply operates as a completely separate and independent unit, electrically isolated
from the other.
2. Parallel
The output from both units is channelled into the Master unit (right hand side), increasing its
current output capability accordingly. The Master unit then behaves exactly as a single power
supply of increased current capability. The Slave unit (left hand side) becomes inoperative. The
resolution of the current meter is 2mA on the PL330QMD in parallel mode.
3. Series
Operation is as in Isolated mode, except that the Slave positive output terminal is internally
connected to the Master negative output terminal.
4. Tracking
Operation is as for Series mode, except that the Master voltage controls operate on the Master
and Slave units simultaneously. The current limit controls on each unit continue to operate
individually. Tracking accuracy is better than ±0·3% of setting ± 0·1% of full range.
The Slave output switch should always be on. Both outputs are then switched from the Master
output switch.
Remote sensing cannot be used in either Series or Tracking modes, therefore the shorting bars
should be left in place.
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