Specifications

3–12 System Installation Recommendations
Publication 1747-6.2
Periodic Tests of Master Control Relay Circuit
Any part can fail, including the switches in a master control relay
circuit. The failure of one of these switches would most likely cause
an open circuit, which would be a safe power-off failure. However,
if one of these switches shorts out, it no longer provides any safety
protection. These switches should be tested periodically to assure
they will stop machine motion when needed.
The printed circuit boards of the controller must be protected from
dirt, oil, moisture and other airborne contaminants. To protect these
boards, the controller must be installed in an enclosure suitable for
the environment. The interior of the enclosure should be kept clean
and the enclosure door should be kept closed whenever possible.
Regularly inspect your terminal connections for tightness. Loose
connections may cause improper functioning of the controller or
damage the components of the system.
!
ATTENTION: To ensure personal safety and to guard
against damaging equipment, inspect connections with
incoming power off.
The National Fire Protection Association (NFPA) provides
recommendations for electrical equipment maintenance. Refer to
article 70B of the NFPA for general requirements regarding safety
related work practices.
Preventive
Maintenance