Operation
The operation of both outputs is identical; the following description applies to both.
Setting Up the Output
With the POWER switch on (l) and the OUTPUT switch off the output voltage and current limit can be accurately preset using the VOLTAGE and CURRENT controls; the upper meter shows the set voltage and the lower meter shows the set maximum current.
When the OUTPUT switch is switched on, the OUTPUT ON lamp and the CV (constant voltage) lamp light; the upper meter continues to show the set voltage but the lower meter now shows the actual load current.
Constant Voltage
The output voltage is adjusted using the coarse and fine VOLTAGE control; the CURRENT control sets the maximum current that can be supplied.
The CV lamp lights to show constant voltage mode.
Constant Current
If the load resistance is low enough such that, at the output voltage set, a current greater than the current limit setting would flow, the power supply will automatically move into constant current operation. The current output is adjusted by the CURRENT control and the VOLTAGE controls set the maximum voltage that can be generated.
The CI lamp lights to show constant current mode.
Instantaneous Current Output
The current limit control can be set to limit the continuous output current to levels down to 10mA. However, in common with all precision bench power supplies, a capacitor is connected across the output to maintain stability and good transient response. This capacitor charges to the output voltage and
Power Limit
The maximum output at different voltage settings is limited by the power envelope illustrated below:
The power envelope is set to give 35V/5A and 12V/10A under all supply conditions (both outputs loaded); at lower output voltages the output power is restricted by the 10A current maximum.
When the power limit is exceeded, the status indication will change from CV or CI to UNREG. For example, if the supply is set to 14V, with the current limit at maximum, and is connected to a 3.5Ohm load, 4Amps will flow and the supply will be in CV mode. As the voltage across the load is increased, the power into the load increases until, at about 25V, the power limit is exceeded and the supply changes from CV to UNREG.
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