Omron S8M - Dielectric Strength Test

Digital Multicircuit Protector S8M 21
Input Voltage
Input voltage range: 19.2 to 26.4 VDC
The S8M provides abnormal voltage protection. All branch outputs
will be cut off if the input voltage exceeds 28.8 VDC. This function,
however, does not protect loads and internal parts from high voltages
in all cases. Be sure the input voltage is within the rated range.
Outputs may be cut off by the abnormal voltage protection with loads
that generate reverse peak electromotive force.
The S8M operates by DC input. Do not connect AC input to power
input terminals.
Input Power Supply Selection
The overcurrent protection characteristics of the power supply
connected to the input side can cause a voltage drop, resulting in
tripping.
If the capacity of the input power supply is too small compared with
the load, the overcurrent protection characteristics of the power
supply can cause the failure of S8M operating or tripping by voltage
drop occasionally.
If the input power supply starts or stops too slowly, the overcurrent
protection characteristics of the power supply can cause the failure of
S8M operating or tripping by voltage drop occasionally.
Tripping Performance
When abnormal tripping operates, always remove the cause of the
output first and then reset the alarm.
When using a load with a fixed power operation, the S8M may cause
tripping when the power supply is turned OFF.
Internal parts may possibly be deteriorated or damaged. Do not
repeatedly perform tripping or recovery operations more than
necessary.
Tripping performance depends on the ambient operating
temperature. Use the S8M within the derating curve shown in the
derating curve diagram on page 6.
Dielectric Strength Test
The S8M is designed to withstand 500 VAC for 1 minute between I/O
terminals, all output signal terminals, the external tripping input
terminals, and all communications terminals of the S8M.
The S8M may possibly be damaged from the impulse voltage if a
testing device switch is used to abruptly apply or shut off 500 VAC.
Increase the applied voltage gradually using the voltage adjustment
on the testing device.
Always short the specified terminals so that the voltage is applied to
all of the terminals at the same time.
Power input terminals and branch output terminals are not isolated.
Do not perform dielectric strength tests or other insulation appraisal
testing between inputs and outputs.
External Tripping Input
When using the external tripping input, always confirm the
application methods described in the S8M User's Manual (Cat. No.
Z241) before designing the system.
Display
The voltage detection function monitors the voltage at the power
input terminals. Measure the voltage at the branch output terminals
to confirm that the output voltage is correct.
Backup Device Connections
Observe the following precautions when using a backup device, such
as one from OMRON's S8T Series.
• When connecting a backup device to an S8M branch output, the
backup current will be supplied to other branches through internal
circuits and it is conceivable that internal parts may be deteriorated
or damaged at the same time. When using a backup device with
the S8M, connect the backup device to the power input side.
• When connecting a backup device to the S8M input side, the
backup time will be shorter than normal due to internal power
consumption. Always confirm the backup time when using a
backup device.
Startup Delay
The startup delay will not operate when a relay or other device is
used for ON/OFF control on the output side of the S8M, so a tripping
operation may occasionally occur.
Connections
It is possible to connect S8M like below.
Series connections, such as connecting an S8M to the output of
another S8M, are not possible.
+V
−V
+V
−V
+V
−V
−V
+V
−V
+V
−V
+V
−V
+V
−V
+V
−V
+V
−V
+V
−V
+V
Power
supply
S8M
S8M
Correct
Incorrect
+V
−V
−V
+V
−V
+V
−V
+V
−V
+V
V
V
+V
−V
Power
supply
S8M
S8M