Aim-TTI LD400, Инструкция по эксплуатации

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Enabled , or when the Transient level control key is selected, or (if the slow start circuit is active)
when the source voltage rises above the Dropout Voltage threshold.
It is also possible to use the External Analogue Voltage control mode to generate transients of
any required shape by using an external generator to produce the required waveform. This is
also controlled by the
Extern menu (page 27). Note that the external signal still passes through
the internal slew rate control circuits, so appropriate Slew Rate settings need to be made.
To end Transient operation (whether internal or external) and return to a constant level press
either the
A or B key (in the
LEVEL SELECT
section) as required.
Transient Menu
Press the Trans soft-key on the home screen to enter the Transient menu which gives access to
the controls for the Frequency and Duty Cycle of the internal oscillator and the Slew Rate
settings which apply to all changes in level, however caused.
These parameters can also be changed using the
∆
ADJUST
facilities described previously, but to
do this the unit must be on the home screen not the Transient menu.
Note that changes to the transient frequency or duty cycle do not take effect until the end of the
present cycle, at the return to Level A. This is particularly noticeable at very low frequencies.
Disabling and then re-enabling the load input will also immediately start a new cycle.
Transient Frequency
The repetition rate of the internally timed transients can be set in terms of frequency or period.
Pressing the
Freq or Period soft-key on the Transient menu opens the Frequency and Period
setting menu. A new value can be entered, in the present representation, in the usual manner.
Two soft-keys labelled
Freq and Period allow the alternative representation to be chosen. Press
the Back soft-key to return to the transient menu or the Home key to return to the home screen.
The soft-key label on the transient menu will show either Freq or Period to reflect the most
recent choice of representation.
Transient Duty Cycle
Pressing the Duty soft-key on the Transient menu opens the Duty cycle setting menu. This
setting specifies the percentage of each repetition spent at the Level A setting, including the
transition from Level B to Level A; the transition back to Level B and the time stable at that
setting occupies the remainder of the cycle.
The available duty cycle range is 1% to 99%, but note that the time duration of each portion of
the cycle must be sufficient for the transition defined by the Slew Rate and Level settings to
occur; otherwise the load will never reach the steady state at the set value before the next
transition in the opposite direction starts. This error condition is discussed below. Press the
Back
soft-key to return to the Transient menu or the Home key to return to the home screen.
Slew Rate
Pressing the Slew soft-key on the Transient menu opens the Slew Rate setting menu. This Slew
Rate setting sets the slope of the transitions between the two level settings. It applies to all
changes in level whether caused by manual setting, adjustment using the knob, the internal
transient generator or external voltage control. It is also used to determine the rate of rise and fall
when the Slow Start circuit is triggered.
The slew control circuit introduces a small additional error into the accuracy of the level settings,
which varies depending on the actual Slew Rate setting. If the dynamic facilities of the load are
not being used, then the
Default soft-key sets the circuit to the calibrated state for best accuracy.
The circuit provides a linear transition in the control value of the active mode, so, for example, in
Constant Power (CP) mode the slew rate is expressed in Watts per microsecond, Watts per