Gossen MetraWatt METRAHit 28C light - Current Sink - Simulation of a 2-Wire Transmitter; Current Source; 7 Current Source and Current Sink

10 GOSSEN METRAWATT GMBH
7 Current Source and Current Sink
➭ Connect the device under test with the measurement ca-
bles.
➭ Select the mA current sink calibration function or
mA current source with the rotary switch.
➭ Press Esc until you enter the range selection menu.
➭ Select the desired range:,
0 … 20 mA, 4 … 20 mA or 0 … 24 mA,
with the #" keys.
➭ Press the ↵ key to enter the output menu.
➭ Setting the simulation value:
The decade (i.e. the position of the digit to be changed) is
selected with the $ ! keys, and the respective digit is
set with the #" keys.
ON indicates that the current source is active.
7.1 Current Sink – Simulation of a 2-Wire Transmitter
A current sink (0 … 24 mA) or current loop load can be simu-
lated with this function. The calibrator regulates the current,
which flows via the calibrator jacks from an external power
supply, independent of direct voltage applied to the jacks
(4 … 27 V). The caliibrator varies the internal resistance such
that the adjusted current value flows.
Note!
☞
The latest adjusted simulator range is stored to mem-
ory. Voltage at the calibrator jacks may not exceed
27 V in the current sink operating mode, because
thermal overload would otherwise occur and the fuse
F3 would blow.
LoVolt appears at the display where the voltage is too
low.
Example of a 2-Wire Transmitter Measuring Circuit
7.2 Current Source
Internal supply power is used for the simulation of a current
source.
Note!
☞
The internal control circuit of the current source is
monitored: if voltage drops by more than 20 V at the
external burden or if the current circuit is interrupted,
„Hi burd“ appears at the display.
Attention!
!
In this operating mode interference voltages must not
be applied to the calibrator jacks.
In the event of operating errors, such as the short-
term application of a high interference voltage, the in-
strument/calibrator is protected by a replaceable
fuse F3, see chapter 12.3.
Simulation in Percentages (current source only)
➭ Select the simulation function and the output range
(Isink/Isource = 4 … 20 mA) with the rotary switch and
the # key.
➭ Press the ESC and # keys simultaneously.
13.452
NUM ON
SINK
mA
4-20
mA
4-20
NUM
sele t range
mA
#"
Current
#"
Current Value
Range
$ !
ON
SINK
SINK
Range Selection Menu
↵
ESC
(... 2x)
Peripheral Device
24 V
Power
4 ... 20 mA = 0 ... 100 °C
+
+
–
–
Pack
CALIBRATOR
–
+
Output
13.452
NUM ON
SOURCE
mA
0-20
mA
0-20
NUM
sele t range
mA
#"
Current
#"
Current Value
Range
$ !
ON
SOURCE
Range Selection Menu
↵
ESC
(... 2x)