Hitachi HSC-2100 Hardware Manual page 153

6 MAINTENANCE
⑧ Remaining service life of relay contacts
The relays used in contact output modules have a limited service life due to the wear of their
contacts. If a contact output module's relay is intended to be used at rated voltage and rated
current, its expected service life is 100,000 switching operations (1,800 cycles per hour).
When the relay's service life reaches the limit, the contact output module needs to be replaced
with a new one as long as the application using it needs to be used further.
If the input voltage to a power supply module is close to the upper or lower
limit of the prescribed range, ask a power supply management specialist to
perform an inspection even if the input voltage is within the operating
specifications.
Power to the I/O modules mounted in the cubicle must be supplied from a
power supply module with an appropriate wattage rating for the I/O modules.
If a power supply module whose wattage rating is lower than expected is used,
it may result in a fire.
Be sure to power down your application system before replacing an existing
module.
Replacing a module in a power-on condition may cause damage to the
hardware.
NOTICE
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