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Basic Function Details Section 2-4
Alarm and Tripping
Operation When
Overcurrent/
Abnormal Current
Occurs
The following example shows the alarm and tripping operation when the over-
current alarm value < abnormal current tripping value. It is also possible to set
the overcurrent alarm value > abnormal current tripping value.
Safety Functions
Short-circuit Protection
Fuse
If an error occurs that prevents the semiconductor relay from cutting off a
branch output's current, the short-circuit protection fuse will blow to protect
the circuit.
Note If the fuse blows, that branch output cannot be used.
Thermal Fuse If an error occurs that prevents the semiconductor relay from cutting off a
branch output and the temperature of the S8M's internal resistors rises abnor-
mally high, the S8M's thermal fuse will blow to prevent a fire hazard.
Note If the fuse blows, that circuit cannot be used.
Safety When Cycling
Power from Test Mode
If the S8M is turned OFF in Test Mode, all branch outputs will be disconnected
when the power is turned ON again. This is because the connection/discon-
nection settings have not been completed, so all outputs are disconnected to
ensure safety. After completing connection/disconnection settings in Test
Mode, always change to Run Mode or Setting Mode before turning OFF the
power supply.
2-4-2 Overvoltage/Undervoltage Protection Function
Abnormal Voltage
Tripping
When the input power supply voltage exceeds 28.8 V (see note), all of the
branch outputs will be cut off and the seven-segment display will indicate error
code A10. It is not necessary for the user to set any parameters for this func-
tion.
Note The voltage is measured at the power input terminals.
Power supply
voltage
Branch output
current
Branch output
voltage
Alarm Output
(ALM)
Tripping Alarm
Output (TRP)
Reset signal
Abnormal tripping current value
Overcurrent alarm value
3 s
OFF
ON
ON
OFF
ON
ON
Tripping
operation
Seven-segment
display
Outputs Conditions required
to reset
28.8 V min.
20 ms max.
Alternately displays
error code A10 and
the voltage.
The Tripping Alarm
Output (TRP) is
turned OFF.
Voltage below 28.5 V
and 15 s elapsed
after output is cut off.
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