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DLRO®200
6
Safety warnings
1. Safety warnings
THESE SAFETY WARNINGS MUST BE READ AND UNDERSTOOD BEFORE THE INSTRUMENT IS USED.
DLRO200 is supplied without a plug terminating the supply lead.
An appropriate plug must be fitted prior to use.
The DLRO200 must be grounded (earthed) when in use.
The instruments need a ground connection for two reasons.
As a safety ground.
To provide the internal voltmeter with a ground reference, so that it can alert the user if a dangerous voltage
is connected to the terminals.
At switch on, an interanl test circuit checks that the ground wire is connected. A single-phase supply normally
has one live wire one neutral wire and a ground. The neutral is connected to ground at some point, so that
neutral and ground are both at approximately the same voltage. At switch-on there is a continuity check from
ground to neutral. (There is also a check from ground to live in case the power leads are reversed). If there is
no continuity the instrument will refuse to start and the screen will remain blank.
This system works well when power is taken from a supply where there is one live phase wire and a neutral
which is at ground potential. A problem arises when power is obtained from a portable generator where the
two supply wires are floating. Connecting the DLRO ground to real ground makes it safe but the internal test
circuit does not work because there is no connection between ground and the power wires.
The solution to the problem:
Connect the ground terminal to real ground (for safety).
Connect one of the power wires to ground (to enable the ground test circuit).
It is a good idea to also connect the generator chassis to ground (for safety).
Circuits must be de-energised before testing.
The DLRO200 must only be used on dead systems. If the item under test has a voltage upon it greater than 10
volts ac peak or dc with reference to ground the DLRO200 will indicate the presence of the voltage and prevent
any tests being carried out.
Testing inductive circuits can be hazardous:
The DLRO200 is a high power instrument, designed for testing resistive loads. It must NOT be used to test
inductive loads.
During use the DLRO200, its current leads and the sample being tested can become hot.
This is normal and is caused by the passage of high currents. Take care when touching the instrument, current
leads, clips and the test sample.
This product is not intrinsically safe. Do not use in an explosive atmosphere.
Ensure that the power switch is always accessible so that power can be disconnected in an emergency.
If this equipment is used in a manner not specified by the manufacturer, the protection provided by the
equipment may be impaired.
1.1 Installation category definitions
CAT II
Measurement category II: Equipment connected between the electrical outlets and the user’s equipment.
CAT III
Measurement category III: Equipment connected between the distribution panel and the electrical outlets.
CAT IV
Measurement category IV: Equipment connected between the origin of the low-voltage mains supply and the
distribution panel.
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