KEPCO MBT Series - Manual (Page 40)

3-2
MBTSVC111609
3.1.2 COMMANDED MODE
Two commands are available from the keypad (either locally or remotely) or, in a different form,
from a remote computer: Voltage mode and Current mode. After a Voltage mode command has
been issued, the power supply is considered to be in commanded Voltage mode; after a Current
command, the power supply is in commanded Current mode. These commands can not change
the actual mode. This means, for example, that the power supply can be in commanded Voltage
mode (Voltage mode command issued) and actual Current mode because R
L
< V
PROG
/I
PROG
.
The commanded mode is important during remote operation because it establishes which con-
ditions the internal microcontroller of the power supply will monitor to determine whether an
error condition exists. For commanded Voltage mode the power supply reports a “voltage error”
if the output voltage exceeds the internal limits established for output voltage, and an “overload”
error if the output current reaches the programmed value for Current Limit. For commanded
Current mode the power supply reports a “current error” if the output current exceeds the inter-
nal limits established for output current, and an “overload” error if the output voltage reaches the
value programmed for Voltage Limit. Error messages are not used when operating in Local
mode.
When Models MR and MGR are in commanded Voltage mode, the slew keys are assigned to
increase/decrease output voltage, and when the output is disabled (DC OFF pressed), the out-
put relays isolate the output from the load by disconnecting the output. Commanded Current
mode assigns the slew keys to increase/decrease current, and causes the output relays to iso-
late the output from the load by short-circuiting the output. This feature fully protects the load
regardless of commanded mode. When the output is enabled (DC ON pressed), the output
relays either connect the output to the load (commanded Voltage mode) or remove the short-cir-
cuit from the output (commanded Current mode).
For Models M and MG, commanded mode has virtually no effect on local operation with one
exception: if the unit was commanded to Current mode through remote operation prior to enter-
ing Local mode, the slew keys will be assigned to increase/decrease current until the first Volt-
age mode command is received from the keypad. After receiving a Voltage mode command, the
slew keys will be assigned to increase/decrease voltage. Subsequent Voltage and Current
mode commands have no effect; “No relay present” is displayed and the slew keys remain
allocated to voltage.
3.1.3 LOCAL MODE
In local mode, Voltage and Current can be set either via the front panel keypad or the VOLTAGE
and CURRENT controls (PAR.s 3.2.1.6 and 3.2.1.7). A pair of up/down slew controls provide an
alternate way to control the output incrementally. Selected keys on the keypad serve a dual pur-
pose. These keys are identified by the alternate function labeled in blue; the alternate function is
accessed by pressing the SHIFT key prior to the dual function key.
A local programming feature (PAR. 3.2.1.11) allows the power supply parameters to be preset
and applied for a specified period of time. The Power Supply can be programmed to sequence
through as many as 89 steps which may be divided into a maximum of 10 programs.
A menu feature (PAR. 3.2.2) guides the operator through various operational sequences, includ-
ing power supply calibration and remote operation of another power supply using the local key-
pad.