User manual

LABKON Series
_________________________________________________________________________________________________
50 GMC-I Messtechnik GmbH
5 Tutorial
5.1 Tutorial
The GOSSEN METRAWATT LABKON Series is a high performance instrument capable of delivering clean DC power. But to
take full advantage of the performance characteristics designed into the power supply, certain basic precautions must be
observed when it is connected for use on the lab bench or as a controlled power supply. This chapter gives specific details on
the operation of the GOSSEN METRAWATT LABKON Series power supply.
5.2 An Overview of GOSSEN METRAWATT LABKON Series Operation
The GOSSEN METRAWATT LABKON Series has a very precise regulating properties and respond quickly to variations of
the line and load. These supplies also exhibit low ripple and noise, are hardly affected by ambient temperature changes, and
are distinguished by circuit simplicity and a high degree of reliability.
The GOSSEN METRAWATT LABKON Series is controlled by a control circuit that provides voltages to program the outputs.
The power supply sends the output voltages back to the control circuit. The control circuits receive information from the front
panel and send instant information to the display. At the same time, the control circuit also receives and returns the
corresponding values over the remote interface.
The remote interface is isolated from the control circuit and the power supply.
5.3 Output Characteristics
An ideal constant-voltage power supply would have a zero output impedance at all frequencies. Thus, the voltage would
remain perfectly constant in spite of any changes in output current demanded by the load. The ideal constant-current power
supply exhibits infinite output impedance at all frequencies. Thus the output voltage of the ideal constant-current power
supply would change correspondingly when a load change occurred in order to maintain its output current at a constant
value.
Ideal Constant Voltage Mode Ideal Constant Current Mode
The GOSSEN METRAWATT LABKON Series power supply outputs can operate in either constant-voltage (CV) mode or
constant-current (CC) mode. Under certain fault conditions, the power supply can not operate in either CV or CC mode and
becomes unregulated.
The graph below shows the operating modes of the three outputs of the power supply. The operating point of the supply will
be either above or below the line RL = RC. This line represents a load where the output voltage and the output current are
equal to the voltage and current setting. When the load RL is greater than RC, the output voltage will dominate since the
current will be less then the current setting. The power supply is said to be in constant-voltage mode. The load at point A has
a relatively high resistance value (compared to RC), the output voltage is at the voltage setting, and the output current is less
than the current setting. In this case the power supply is in the constant-voltage (CV) mode and the current setting acts as a
current limit.