Bid Package 08 North Well Field - Garney Construction

3. Safety Function Wiring:
a. Emergency shutdown switches shall not be wired into the controller.
4. An emergency power disconnect shall be placed in the power circuit feeding the power
supply as a means of removing power from the entire PLC system.
a. Capacitor shall be placed across the disconnect to protect against current outrush
through trails.
5. Safe Wiring:
a. Equipment failure mode shall be selected so that the loss of power or control signal
to the equipment will result in the equipment either shutting down or operating
safely.
b. Activation of alarms and stopping of equipment shall result from the deenergization
of control circuits, rather than the energization of control circuits.
c. Low voltage control signal wires:
1) Place in conduit segregated for that purpose only
2) Twisted shielded wire pair
Not located in the same conduit or bundle with power wiring
6. Initial Safety Conditions:
a. Utilize program module to dictate output states in a known and safe manner prior
to running of control program.
b. Utilize program each time PLC is re-initiated and the control program activated.
7. PLC Fault Relay:
a. Placed in series with any other emergency stop conditions
b. Opening of PLC Fault Contact:
1) Upon unsafe or undesirable system operation, including:
c. Loss of memory
d. Processor fault
e. Power supply fault
f. Isolation failure
g. Communications failure
h. Isolation failure
i. Communications failure
j. Scan time overrun
k. Module failure
l. Scan time overrun
m. Module failure
8. Monitoring of Internal Faults and Display:
a. Internal PLC system status and faults shall be monitored and displayed. Monitored
items shall include:
1) Memory ok/loss of memory
2) Processor ok/processor fault
3) Battery ok/battery low
4) Power supply ok/power supply fault
5) Isolation failure
Supervisory Control and Data Acquisition (SCADA) System 40 90 02-14
CMD11269 – Ward County Transmission System Expansion – Contract C – Above Slab TPS, OPS, and WPS