KEPCO JQE 150-1.5MVPY-26956 Half Rack - Manual (Page 27)

JQE SPECIAL SVC 081111 3-3
3.3 OUTPUT ADJUSTMENT
Once the load is connected to the output terminals of the power supply as described in the pre-
vious paragraphs, the operating voltage may be adjusted to the desired value by turning the
VOLTAGE CONTROL and observing the front panel VOLTMETER.
If the link is present between terminals REF and RPC1 of barrier strip TB502 at the rear panel,
CURRENT LIMIT CONTROL “A” is recommended to be set fully clockwise, then use either
CURRENT LIMIT CONTROL “B” or the remote resistance connected between terminals RPC1
and RPC2 of barrier strip TB502 to control the current limit.
If the link is removed between terminals REF and RPC1 of barrier strip TB502 at the rear panel,
both CURRENT LIMIT CONTROL “B” and the remote control of current limit via terminals RPC1
and RPC2 are disabled; use CURRENT LIMIT CONTROL “A” to establish the current limit.
CURRENT LIMIT CONTROL “A” or “B” may also be set to intermediate values, as desired, by
first turning the AC POWER circuit breaker to the "off" position and then placing a short circuit
across the output. Turn AC POWER circuit breaker "on." Now the required operating current is
adjusted by turning CURRENT LIMIT CONTROL “A” or “B” to the value needed. For a more pre-
cise current limit adjustment use a 4-terminal shunt connected at the output as specified in PAR.
2.5 step 7. The range for current limit “A” is 10% to 100% of I
O
nominal “A.” The range for cur-
rent limit “B” is 1% to 105% of I
O
nominal “B.” Turn off the unit and remove the short-circuit or
shunt. After the short is removed from the output, the voltage protection can be set.
With the OVP ADJ potentiometer set fully clockwise, set the output voltage as described above.
Turn the OVP ADJ potentiometer slowly counterclockwise, until the power supply output "crow-
bars," indicated by the output voltage going to zero and the circuit breaker tripping. Turn the
OVP ADJ potentiometer 1/4 turn clockwise. A too close adjustment towards the operating volt-
age may lead to spurious triggering, especially if the "delay" adjustment is set for maximum sen-
sitivity. The minimum "threshold" voltage protection adjustable is 5% of E
O
nominal. Adjust the
OVP DELAY ADJ potentiometer if required. This control is factory adjusted for maximum sensi-
tivity, consistent with reliable operation without spurious triggering. It needs re-adjustment only if
extremely sensitive loads must be triggered in the shortest time possible and if some spurious
triggering can be tolerated. Now the load can be connected to the power supply and operation
can commence.
3.4 INTRODUCTION TO REMOTE PROGRAMMING
3.4.1 GENERAL
A few general remarks may be in order to familiarize the user of this equipment with the termi-
nology and basic equations pertaining to remote programming of Kepco Power Supplies. Elec-
trically, the power supply, consists of the unregulated DC source (E
U
), the pass element (E
P
),
the DC error amplifier (A
V
) and a comparison circuit which resembles a four-arm electrical
bridge. (Refer to Figure 3-3). The elements of the bridge are arranged to produce a virtual zero
at the amplifier input when the bridge circuit is at balance (VAA' = 0). Any tendency for the out-
put voltage to change in relation to the reference voltage (E
r
) creates an error signal (E) which,
by means of negative feedback and the amplifier, tends to correct the output voltage towards
restoration of bridge balance.