Hioki Super megohm SM7110 - Circuit Diagram of the Switching Unit; Including Current-Limiting Resistor (Protective Resistance) and Relay

Appx.11
Assembling Switching Unit for Objects to be Measured
Circuit diagram of the switching unit
To connect between the measurement leads and the instrument or between the leads and objects to be
measured, employ the connectors that are custom-made by Hioki for use with the Super Megohm Meter.
In addition, as for the cables between the instrument and the switching unit and between the switching unit
and objects to be measured, employ the cables that are custom-made by Hioki for use with the Super Megohm
Meter.
Hioki-made special
connector for Super
Megohm Meter
Connects to the
instrument
Connects to Object 1
Current-limiting resistor
(protective resistance)
Connects to Object 3
Connects to Object 2
Connects to Object 4
Including current-limiting resistor (protective resistance) and relay
Guard and shield
When connecting a relay and a current-limiting resistor (protective resistance) to the instrument, pay attention
to the guard and shield.
See the following example (The guard prevents DC interfering currents from owing, whereas the shield
prevents AC interfering currents from owing).
← Object to
be measured
Instrument →
Hioki-
made cable
for Super
Megohm
Meter
Hioki-
made cable
for Super
Megohm
Meter
Ground
Shield case (metallic)
Shield (guard) terminal of relay
Insulator
Metal terminal
Guard
(metallic)
Current-limiting resistor
(Protective resistance)
To form the shield case, not only metallic sheets but also metallic
mesh sheet can be used. However, it should be rigid (because noise is
generated due to electrostatic coupling if vibration bends it).
Appx.