KEPCO MBT Series - Manual (Page 57)

MBTSVC111609
3-19
If the output is enabled and the value of the load is less than the value of programmed voltage
divided by programmed current (R
L
< V
Prog
/ I
Prog
), the power supply operates in Current mode
and the VOLTAGE control adjusts actual voltage limit. This will not be apparent from the display
indication; to see the revised voltage limit it is necessary to view status by pressing SHIFT then
(.) on the keypad.
3.2.1.7 SETTING OUTPUT CURRENT OR CURRENT LIMIT
There are three ways to set output current or current limit: 1) Iadj and numeric keys, 2) slew
keys, 3) the CURRENT control. The display should be reading either “Output is off” (PAR.
3.2.1.5.2, step 1) if the output is disabled, or “Keypad control” (PAR. 3.2.1.5.1, step 2) if the
output is enabled.
NOTE: If the power supply is operating in a remote configuration, the operation of Local con-
trols can be influenced by the last mode command sent via remote mode before the
unit was set to Local mode. For this reason it is advisable to set the power supply
mode locally using SHIFT then Vadj (commanded Voltage mode) or SHIFT then Iadj
(commanded Current mode) before setting current/current limit values
3.2.1.7.1 USING IADJ AND NUMERIC KEYS — M, MG MODELS
The Iadj and numeric keys can be used to adjust either output current or current limit (either the
actual value or the programmed value). The effect of the numeric keypad entries is dependent
upon the model, commanded mode, whether the output is enabled or disabled, and the load.
For M and MG models, when the output is disabled, the load is disconnected from the power
supply. If the load is enabled, the power supply will operate in voltage mode except for the case
where the value of the load is less than the programmed voltage divided by the programmed
current (R
L
< V
Prog
/ I
Prog
). In this case the MBT power supply will be forced into Current mode.
Table 3-9 (M, MG Models) summarizes the effect of the Iadj and numeric keys for different con-
ditions. The first three columns reflect the status of the unit before the Iadj command is issued.
The fourth column shows the message on the front panel display after the Iadj key is pressed
and the fifth column shows how the adjustment will affect the status of the power supply. Refer
to PAR.s 3.1.1 and 3.1.2 for more details regarding commanded and actual mode of operation
(either voltage or current).
Table 3-9 shows that with the power supply operating in Voltage mode, with the output disabled,
Iadj and keypad entries adjust the programmed current limit.
If the load is enabled and the value of the load is greater than or equal to the value of pro-
grammed voltage divided by programmed current (R
L
≥ V
Prog
/ I
Prog
), the power supply operates
in Voltage mode and the Iadj and keypad entries adjust actual current limit.
If the load is enabled and the value of the load is less than the value of programmed voltage
divided by programmed current (R
L
< V
Prog
/ I
Prog
), the power supply is forced to operate in cur-
rent mode and the Iadj and keypad entries adjust actual output current.