User manual

GMC-I Gossen-Metrawatt GmbH 11
2 Preparation for Operation and
Initial Start-Up
2.1 Connection to the Mains
Observe WARNING I!
CAUTON!
Before switching the KONSTANTER on, make sure that your local mains
voltage corresponds with the operating voltage specified on the
instrument’s rear panel.
The KONSTANTER requires 230 V~ supply power. Connect the
recessed mains plug at the back of the device to a mains outlet
with earthing contact with the included power cable.
Power consumption is specified on the serial plate at the back of
the KONSTANTER.
A mains outlet socket is located above the recessed plug and
can be used for looping mains power through to additional
instruments.
This mains outlet is neither switched nor fused.
WARNING!
If mains power is looped through, make sure that overall power
consumption does not exceed 10 A at the point from which power is
drawn from the mains!
Suitable “mains jumper cables” are available as an accessory (see
order information on last page).
2.2 Connection to the Consuming Device
Supply power to the consuming device is connected either at the
front panel with 4 mm safety plugs to the safety jacks identified
with the “+” and “−” markings, or to the “+” and “−” outputs at the
6-pole terminal strip at the rear panel.
Connections for the consuming device at the rear panel include two
“ + ” and two “ − ” terminals.
These must be connected in parallel for load currents of greater than 10 A
due to contact ratings.
Be certain to use conductors with an adequate cross-section and observe
correct polarity. It is advisable to twist the power leads to the consuming
device, and to identify polarity with markings at their ends.
If connections are made simultaneously at the front and the rear
panel, constant voltage regulation applies to the terminals at the
rear panel. This is not permitted for parallel connection because the
internal connection might otherwise be overloaded.
The yellow-green safety jack at the front panel is connected to PE,
and can be used to connect earthing cables or cable shields, or as
an earth connection point for one of the output terminals.
2.3 Sensing Mode Operation
In order to take advantage of highly constant output voltage, even
if long leads are used for connection to the consuming device,
voltage drops at the power leads can be compensated for with
additional sensing leads.
Function
• Sensing terminals: +SENSE / −SENSE
Output voltage, which is decisive for the voltage measuring and
regulating circuits, is acquired directly at the consuming device
(instead of at the output terminals).
• Sensing mode operation (remote sensing) offers the following
advantages:
+ Voltage at the consuming device remains largely uninfluenced
by current-dependent voltage drops at the power supply leads
during constant voltage operation.
Voltage drops are compensated for by automatically
increasing voltage as required at the output jacks.
+ Voltage limiting remains uninfluenced by output current as well
during constant current operation.
+ The voltage value determined by the measuring function
corresponds to voltage acquired by the sensing leads. Load
parameters such as power consumption and load impedance
can thus be more precisely determined.
• The parameters and limit values listed in figure 2.3 apply for
operation with sensing leads.
Figure 2.3 Connection to Consumer for Sensing Mode Operation
• C
s+
, C
s-
typically ... 220 μF
• U
s+
,U
s-
≤ 1 V
• I
s+
− U
s+
/ 81 Ω
• I
s-
U
s–
/ 81 Ω
Connection
• The +SENSE and –SENSE leads from the output plug connector at
the rear panel should be connected as close as possible to the
corresponding terminals at the power consuming device.
• Interference injection can be minimized as follows:
☞ Twist the sensing leads and/or
☞ Shield the sensing leads.
(Connect shield to ground/housing or neg. output terminal.)
• Impedance resulting from long power and sensing leads may lead to
control oscillation at the output.
Capacitance at the consumer promotes this problem as well.
• Control oscillation can be counteracted by connecting
capacitors (C
s+
, C
s-
) between the SENSE and the output terminals
(see figure 2.3).
• Twisting the power leads reduces their impedance as well.
• Incorrect connection of the sensing leads does not cause any damage
to the KONSTANTER, although it results in the following reversible
events:
+ Sensing lead polarity reversal or power lead interruption
If output voltage from the KONSTANTER is not limited with the
current regulator, it rises to well above the setpoint value.
Overvoltage protection is then immediately triggered and the
output is deactivated.
+ Sensing lead interruption
If one of the sensing leads is interrupted, the device is
switched automatically to local sensing for the
corresponding output terminal.
• If the sensing leads are connected incorrectly, voltage present
at the output terminals or consuming device is not displayed.
Activating Sensing Mode Operation
• Sensing mode operation is activated automatically after
connecting the SENSE terminal to the consumer which has
been connected to the output terminals.
• Sensing mode operation is deactivated as soon as this
connection has been interrupted.