Hitachi HSC-2100 Hardware Manual page 35

1 GENERAL INFORMATION
(6) Noise
Do not install the programmable controller in or near to a panel in which an inverter or other
high-voltage device is installed. If such installation is essential for some reason, set
shielding plates to protect the CPU unit or I/O unit and the cables from the influence of
electromagnetic or electrostatic induction or both.
(7) Emergency stop circuit
Should a component part of the programmable controller fail, it may affect the entire product.
The emergency stop circuit to be integrated into the product must be constructed with an
external relay circuit.
(8) Replacement of component parts
Customers are not recommended to replace any component part of the programmable
controller not mentioned in this manual. If a faulty part is found, replace the module
containing it. The replacement of a component part other than those mentioned in this
manual should be done by Hitachi's maintenance personnel.
(9) Replacement of modules
Before replacing a module, be sure to switch off the power supply.
Without doing so, such replacement may result in product failure or electric shock.
(10) Expansion of the existing equipment
If the existing equipment of the programmable controller is expanded by adding additional
units, check the expanded equipment for any abnormality, according to the instructions given
in Section 6.1, "Preventive Maintenance," and make sure that the programmable controller
functions normally. For the power supply and grounding used, in particular, check the
following items:
Power supply checkup
Check the voltage and its waveform.
• Make sure that no voltage drop is caused.
• Make sure that the amount of noise in the power line is not problematic.
Power
supply
voltage
Too much noise
Normal waveform
Abnormal waveforms
Skewed wave
1-12
I/O unit
Trapezoid wave