Seaward DO5000 Series User Manual

Page 26

Operating Instructions

Microhmmeter Type DO5000

5 Measuring with the DO5000

5.1 Connecting to the DO5000

The DO5000 uses a four terminal method of measurement which eliminates errors due to lead
resistance. The measuring leads plug into the four front panel safety sockets. The sockets are
marked +U, -U, +I, & -I. Connections to the resistance to be measured should be as per Figure
5.1.1

Figure 5.1.1 Connection diagram

NOTE: It is important to connect the I (current) leads outside the U (potential) leads

5.2 Connecting to the resistance

The Digital Microhmmeter DO5000 employs a four wire method of measurement, i.e. it is
necessary to make four connections to the resistance under test. The instrument is supplied
with four leads; two for the potential connections which are made across the test resistor at
the points between which the resistance is to be determined; and two for the current
connections which connect the test resistor to the current supply circuit.

5.2.1 Connect the red leads to the +U and +I sockets and the black leads to the -U and -I
sockets.

5.2.2 Connect to the resistance under test as shown in figure 5.1.1, Cleanliness is important
and if the sample is not clean, a rub with an abrasive paper to remove oxides is recommended.

5.3 It is not always possible to use the combined current and potential crocodile clips (Kelvin
clips), in which case test leads with spade tags, or special fixtures may have to be made to
suit the particular application. We offer a variety of different lead and fixture types which are
list in section 6.1

-I

-U