Connections - Aim-TTI BS407 Bedienungsanleitung

Input Terminals
Connections are provided on the front panel for standard 4-terminal resistance measurements.
The test current flows between the terminals marked FORCE + and – and the voltage across the
unknown resistance is measured between the terminals marked SENSE + and –. To obtain
correct readings the entire measurement circuit should be connected only to the resistance being
measured.
The instrument is supplied with a Kelvin lead set consisting of two special crocodile clips
connected to four 4mm plugs. The upper and lower jaws of each crocodile clip are not electrically
connected: the grey jaws are used as the force terminals and the coloured jaws (red and black)
as the sense terminals. The grey jaws are connected to the plugs which have a grey collar.
Connect these leads to the instrument as follows:
The instrument can be used with any other 4 terminal connection arrangement as required by the
physical size of the resistance being measured.
The measurement circuit is not grounded (even when the battery is charging) but for the safety of
the operator the connections should be within ±30 volts from earth. It is permissible for the circuit
to be externally connected to earth at one point only.
The maximum voltage emitted from the instrument is 6V DC.
Protection
When measuring the resistance of large iron-cored inductors the test current builds a magnetic
field within the core. When this current is removed a back-emf is generated as the field
collapses. Take care when disconnecting the test leads from inductors not to touch the terminals
as the back-emf can give a noticeable electric shock. It is better to depress the Set Zero switch
and allow the instrument to absorb the stored energy before disconnecting the inductor.
Protection circuits within the instrument ensure that it will not be damaged by the back-emf of its
own test current from any inductance.
It is not intended that any external voltage be applied to the input terminals. However, there are
circuits designed to protect the instrument against brief accidental connections. In the case of
more severe misuse fusible resistors protect the internal circuits. These resistors are not
replaceable by the user.
6
Plug
All red
Red with grey collar
All black
Black with grey collar
Connection
Sense +
Force +
Sense –
Force –

Connections