Hitachi SJ Series, User Manual

Page: 638 / 786

18-45
Chapter 18
Tips/FAQ/Troubleshooting
Occurrence

Estimated cause(s)

Exemplar measures to be taken
S8: Motor speed
doesn’t rise.
• The frequency command is low.
• The overload limit function suppresses the current by
dropping the frequency when the output current exceeds the
overload limit level.
• Raising the setting level may improve the situation.
• The overload limit function is at
work.
• The command becomes lower when a more prioritized
frequency command such as for jogging or multi-speed
command is entered. Re-examination of the terminal
function and frequency command destination are required.
• If the upper limiter and the maximum frequency is set to low
level, the situation will be improved by setting them to higher
level. To limit frequencies, use the upper limiter function
instead of the maximum frequency.
• The frequency command is
limited.
• Acceleration time is long.
• If the acceleration time is set long, acceleration becomes
slow. Set the acceleration time short.
Occurrence

Estimated cause(s)

Exemplar measures to be taken
S7: A limit
function is at
work.
• Both [FW] terminal and [RV]
terminals are turned ON by
operation command from input
terminal.
• When the operation permission signal has been assigned,
the operation permission signal needs to be turned ON.
• The operation permission signal
has been assigned to the input
terminal function and the signal
is turned OFF.
• If both [FW] terminal and [RV] terminal are turned ON, input
inconsistency is generated and the inverter stops. Use
only either one of them to operate the inverter.
• Check the operation command direction limit.
• The command is given to the
direction the operation is limited.