ALLEN BRADLEY 1747-L551 PLC Processor

8–2
Starting Up Your Control System
1. Inspect Your
Installation
You can often prevent serious problems in later test procedures by
first making a thorough physical inspection. We recommend that
you do the following:
1. Make sure that the controller and all other devices in the system
are securely mounted.
2. Check all wiring including:
• connections from the main disconnect to the controller input
• the master control relay/emergency-stop circuit
• input device circuits
• output device circuits
Make certain that all wiring connections are correct and that there
are no missing wires. Check the tightness of all terminals to
make certain wires are secure.
3. Measure the incoming line voltage. Be certain that it corresponds
to controller requirements and that it falls within the specified
voltage range. See specifications for input voltage ranges on
page 2–11.
2. Disconnect
Motion-causing Devices
In the following test procedures, the controller is energized. As a
safety precaution, you must make certain that machine motion does
not occur. The preferred way is to disconnect the motor wires at the
motor starter or the motor itself. In this way, you can test the
operation of the starter coil, verifying that your output circuit is
wired correctly and functioning. Similarly, the preferred way to
disconnect a solenoid is to disengage the valve, leaving the coil
connected.
In some instances, you may not be able to disconnect a device the
preferred way. In this case, it is necessary to open the output circuit
at some convenient point.
For circuit testing purposes, it is best to open the circuit at a point as
close as possible to the motion-causing device. For example, your
output might be a relay coil that in turn energizes a motor starter; if it
is impractical to disconnect the motor wires, the next best thing to do
is to open the circuit at a point between the motor starter and the
relay contact.
!
ATTENTION: Machine motion during system
checkout can be hazardous to personnel. During the
checkout procedures 3, 4, 5, and 6, you must
disconnect all devices that, when energized, might
cause machine motion.
Publication 1747-6.2