Hioki ST5520, Instruction Manual, Page: 20 / 201

12
Usage Notes
Before connecting EXT.I/O
WARNING
• External power cannot be supplied to the instrument’s EXT.I/O
connector. Do not apply external power. (The ISO_5V pin of the EXT.
I/O connector is a 5 V (NPN)/-5 V (PNP) power output.)
To avoid electric shock or damage to the equipment, always observe
the following precautions when connecting to the EXT.I/O connector.
•
Always turn off the main power switch on the instrument and on any
devices to be connected before making connections.
• Be careful to avoid exceeding the ratings of external terminals.
(p. 159) During operation, a wire becoming dislocated and
contacting another conductive object can cause serious hazard.
Use screws to secure the external connectors.
CAUTION
To avoid damage to the instrument, observe the following cautions:
•
Do not short circuit ISO_5V and ISO_COM.
•
When connecting the relay coil to the EXT.I/O output terminal, be sure to
install diodes to absorb current-electromotive force.
Before turning the power on
WARNING
•
While insulation resistance is being measured or the START key is
pressed, hazardous voltage may be generated in the measurement
terminal. To avoid electric shock, do not touch the measurement
leads.
•
Before turning the instrument on, make sure that the supply voltage
matches that indicated on its power connector. Connection to an
improper supply voltage may damage the instrument and present
electrical hazard.
CAUTION
•
Avoid using an uninterruptible power supply (UPS) or DC/AC inverter with
rectangular wave or pseudo-sine-wave output to power the instrument.
Doing so may damage the instrument.