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Current Limit
k.Disconnect all loads from the supply.
l.Connect the test setup shown in Figure
m.Set the voltage of the ±20V supplies to 20 volts.
n.Close the load switch and determine the current flow through the current sampling resistor (meter shunt) by measuring its voltage drop with the DVM. The current should be 0.55A±5% (0.5225A to 0.5775A).
o.Check the current limit of the
p.Connect the test setup shown in Figure
output. Close the switch, set the total resistance of RL and the current sampling resistor to an initial value of 2.4 Ω or greater, and set the output voltage to 6 volts.
q.Reduce the value of RL gradually while observing the out- put current indicated by the DVM. The current should increase to a maximum of 2.75A±5% (2.6125A to 2.8875A) before it begins to decrease.
r.Connect a short across RL and then recheck the current indicated by the DVM. The
Load Regulation (Load Effect)
Definition: The change, EOUT, in the static value of dc out- put voltage resulting from a change in load resistance from open circuit to the value that yields maximum rated output current (or vice versa).
To check the load regulation:
a.Connect the test equipment across the output of the +20V supply as shown in Figure
b.Turn on the supply and adjust its voltage to its maximum rated value.
c.Record the voltage indicated on the DVM.
d.Operate the electronic load in open (input off) mode and recheck the DVM indication after reading settles. It should be within 0.01% plus 2mV of the reading in step (c).
e.Repeat steps (a) through (d) for each of the remaining supply outputs.
Line Regulation (Source Effect)
Definition: The change, EOUT, in the static value of dc output voltage resulting from a change in ac input voltage from a minimum to a maximum value (±10% of nominal voltage).
To check the line regulation:
a.Connect a variable autotransformer between the input power source and the power supply line plug.
b.Connect the test equipment across the output of the +20V supply as shown in Figure
c.Adjust the autotransformer for a low line input
d.Turn on the power, adjust the output of the supply to its maximum rated voltage, and record the DVM indication.
e.Adjust the autotransformer for high line voltage input (+10% of nominal voltage) and recheck the DVM indica- tion. It should be within 0.01% plus 2mV of the reading in step (d).
f.Repeat steps (b) through (e) for each of the remaining supply outputs.
Ripple and Noise
Definition: Ripple and noise are measured in the rms or peak-
RMS Measurement
The rms measurement is not an ideal representation of the noise, since fairly high output noise spikes of short duration could be present in the ripple and not appreciably increase the rms value.
To measure the ripple and noise of the rms value on each output supply output:
a.Connect the test equipment across the output of the +20V supply as shown in Figure
b.Turn on the supply and push +20V METER switch.
c.Turn up output voltage to the full rated value.
d.Check that the rms noise voltage at the true rms voltme- ter is less than 0.35mV.
e.Repeat for the remaining supply outputs.
Figure | Figure |
| Setup |