Wayne Kerr AP10030, User & Service Manual

Page: 16 / 70

16 Wayne Kerr AP 1kW Power Supplies • Issue 2
Reset the voltage and current controls of the unit fully anticlockwise. Depress the “output
enable” switch
3 . Note the adjacent green LED 7 is illuminated and that either the CV
(Constant Voltage) or CI (Constant Current) legend is illuminated. Rotate the current
control one turn clockwise and note that only the CV legend is illuminated.
Note: under these conditions of demanding zero output, the ‘UNREG’ legend may also
be illuminated. This indicates that precisely zero output is not being achieved.
Whilst depressing the ‘display OVL’ button 4 , rotate (with a suitable tool) the OVL
adjust control
5
anticlockwise until a reading on the voltmeter of say 25V is reached.
Release the button and rotate the voltage control clockwise at the same time monitoring
the voltmeter. Confirm that when the voltage reaches the level of the pre-set OVL, the
voltmeter reading falls to approximately zero and the OVL legend is illuminated.
Reset the OVL circuit by rotating the voltage control fully anticlockwise, the OVL adjust
fully clockwise, releasing the ‘output enable’ switch and after 5 seconds, depress again to
‘enable’ the output.
Constant Current Check
Inhibit the output by releasing the ‘output enable’ switch, wait 30 seconds for the output
capacitors to discharge and then remove the protective terminal cover held by 2 M3
screws.
Short circuit the +ve and -ve bus bars (use wire capable of carrying the maximum current
that can flow i.e. for 50 amps use 10mm
²
) and then replace terminal cover.
Rotate the voltage control approximately one turn clockwise (from its fully anticlockwise
position) and rotate the current control fully anticlockwise.
Depress the ‘output enable’ switch and confirm that the CI legend is illuminated thus
indicating that the power supply is in constant current mode. Rotate the current control
clockwise. By reference to the front panel digital ammeter confirm that control of the
output current is available over the power supply’s output current range.
Release the ‘output enable’ switch and wait for 30 seconds. Remove the terminal cover
and the short circuit from the output. Replace the terminal cover. Read the remainder of
the operating instructions before connecting supply to actual load.
6.2 Connecting the Load
Load connections to the power supply are made to the busbars (ve and -ve) at
the rear of the instrument. Access to these terminals is gained by removing the protective
cover. Load wires may be connected to any of the three pairs of connecting screws on the
busbars (6 x M5 bolts). Standard wires should have the appropriate size of termination
fitted. It is important that the wires to the load should be of sufficient gauge to avoid
overheating when carrying the current (set by the current limit point) that would flow if
the load were shorted. Generally, thicker wires than the minimum necessary to carry the
current are needed to obtain good regulation at the load. If the load regulation is critical,
then remote sensing should be used (see section 6.4.2.). To eliminate voltage spikes and
noise pick up, which could affect the power supply performance, these leads should be
twisted together, especially when operating with the load at a distance of greater than 1
metre. The leads should also be de-coupled by connecting a 1
µ F capacitor, adequately
voltage rated, across the load and as close as possible to it.