Wayne Kerr AP10030, User & Service Manual

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Wayne Kerr AP 1kW Power Supplies • Issue 2 25
potentiometer. This means that when the ‘output enable’ switch is released, the value set
by the remote programming source appears on the front panel meters.
Terminals 9 and 10 (negative sense and common for programming) on the rear barrier
strip are internally linked. This means that either can be used for negative sense when
connecting for remote programming. The extra terminal is provided for ease of wiring.
The negative sense terminal is used as the common (0V) connection for programming
both voltage and current settings of the power supply. This allows a common ground to
be used when programming the voltage and current remotely.
If voltage programming is being used, an open-circuit input will, in most cases, result in
the power supply output falling to zero. With resistive programming, the outputs could
rise to maximum. To prevent this an ‘upper limit’ programming resistor should be
connected close to the barrier strip terminals. The overvoltage limit may also be used to
give protection against such occurrences.
6.4.4 Auto-Parallel Operation
The AP series of power supplies can be connected for auto parallel operation. This
means that the units can be connected together to give a greater output current capability.
Units are connected together in a ‘master-slave’ configuration. This gives parallel
operation with good current sharing between units.
When in this mode the controls of the master can be operated as if it were a single unit,
i.e. in CV or CI mode, etc. However, current flowing into the load will be current
measured on the master unit multiplied by the number of parallel units in operation.
Notes:
a) Under no (or low) load conditions the down programming speed of the power supply
combination will be considerably reduced. This is because only the master unit will
be able to down programme the output voltage.
b) Not more than four units should be connected together in auto-parallel mode.