KEPCO BHK-MG 200W (Full Rack) Series - Manual (Page 118)

4-4
BHK-MG (OPR) 022014
4.3.3 LOW CURRENT CALIBRATION
1. LCD reads
CONNECT SHUNT <nn OHM >zz A
(nn and zz values are determined by BHK-
MG model being calibrated.; e.g., for BHK 2000-0.1MG, LCD reads
<50 OHM >10 W
).
(Refer to PAR. 4.2 for shunt requirements.) Connect Precision Shunt across power output
terminals (TB1, terminals 2 and 5) and press ENTER.
2. LCD reads
CONNECT DVM TO SHUNT
. Connect DVM (+) input to sense terminal of shunt
connected to output (+), DVM (–) to sense terminal of shunt connected to output (–). Press
ENTER when connections are complete.
3. With LCD reading
Curr ZERO adj.
, monitor DVM and use or keys to increase or
decrease output current as necessary for minimum positive DVM reading. Press ENTER
when complete.
4. LCD will flash
Curr F.S.adj. **WAIT**
then
Curr F.S. adj < >
. Monitor DVM and
use or keys for fine adjustment and 3 or 1 keys for coarse adjustment to increase or
decrease output current as necessary to get V
DVM
reading as close as possible to value
listed below.
V
DVM
= Rs x Io
MAX
(mV)
where
Io
MAX
(mA) is the maximum value of output current (low scale):
BHK 300-0.6MG: 0.6/10 = 0.06A = 60mA
BHK 500-0.4MG: 0.4/10 = 0.04A = 40mA
BHK 1000-0.2MG: 0.2/10 = 0.02A = 20mA
BHK 2000-0.1MG: 0.1/10 = 0.01A = 10mA
Rs (Ohms) is the actual value of the external shunt resistor (the same shunt resistor can be
used for both Low and High scale current calibration).
NOTE: The message
Can’t Adj. Full Scale
is displayed if either the shunt resistor is not
connected to the output terminals during current calibration or if the shunt resistance is
too high. If this occurs, it is necessary to press ENTER followed by RESET to restore
proper operation. Connect the proper shunt across the power output terminals (TB1,
terminals 2 and 5) and refer to PAR. 4.3, step 1 to restart calibration.
5. LCD will show
Curr 10x adj
then
value =____mA
. Monitor DVM and convert V
DVM
to
mA as follows, then note the value of Io
10%LFS
(milliAmps).
Io
10%LFS
(mA) = V
DVM
(mV)/Rs (ohms)
where
Io
10%LFS
(milliAmps) is the 10% full scale value of low range output current (1% of I
OMAX
)
Rs (Ohms) is the actual value of the external shunt resistor (the same shunt resistor can be
used for both Low and High scale current calibration).
6. Use the keypad to enter the value of Io
10%LFS
(milliAmps) noted in step 5 and press ENTER.
If the value is out of range, the message
Out of range
then
Measure again
will be dis-
played. Repeat steps 5 and 6 until directed to proceed to High Current calibration.
7. Press ENTER when complete and proceed to PAR.4.3, step 6.