KEPCO MBT Series - Manual (Page 78)

3-40
MBTSVC111609
3.2.1.11.7 EXITING PROGRAM MODE
To exit Program Mode press CLEAR ENTRY after the program has been stopped (see PAR.
3.2.1.11.6).
1. If the output is enabled when CLEAR ENTRY is pressed, the display reverts to “Keypad
control” (PAR. 3.2.1.5.1, step 2).
2. If the output is disabled when CLEAR ENTRY is pressed, the display reverts to “Output
is off” (PAR. 3.2.1.5.2, step 1), except for Models M and MG where the program was
stopped with RESET: the display reverts to “Keypad control.”
3.2.1.11.8 SAMPLE PROGRAM OPERATION - MODELS M, MG
The following paragraphs describes how the MBT power supply operates, using the Sample
Program (3-17) for illustration. Figures 3-1 (M and MG Models) and 3-2 (MR and MGR Models)
show output voltage and current for the sample program (PAR. 3.2.1.11.2) when R
L
= 2 ohms,
and when R
L
= 1 ohm
NOTE: Whenever a program is running, the STATUS indicators on the front panel represent
the actual condition of the power supply regarding Voltage or Current mode of opera-
tion, the polarity of the output, and whether the output is enabled or disabled.
During step 1, the programmed values of voltage/current with a load of either 1 ohm or 2 ohms
allow the power supply to operate in Voltage mode (current drawn by the load is within the cur-
rent limit of 2.1A).
During step 2, the power supply continues to operate in voltage mode with the 2 ohm load, how-
ever with a 1 ohm load, the power supply is forced into Current mode (even though the com-
manded mode is Voltage mode) since 2V into a load of 1 ohm would produce a current (2A)
greater than the current limit (1.3A). Current is limited to 1.3A and voltage is at 1.3V (1.3A into a
1 ohm load). For MR and MGR Models, since polarity is reversed for this step, Figure 3-2 shows
negative values for voltage and current.
For M and MG models, during step 3 the power supply continues to operate in voltage mode for
the 2 ohm load. For the 1 ohm load, however, current is limited to 3.3A, so the power supply is
forced into Current mode with the voltage at 3.3V (3.3A into a 1 ohm load).
For MR and MGR models, during step 3 the power supply is commanded to operate in Current
mode with the output disabled, so the output/polarity reversal relays short the output, forcing
output voltage and current to zero.