Power And I/O Field Wiring - GE Mark VIe System Manual

6.7 Power and I/O Field Wiring

6.7.1 General Requirements
• Maximum length (unless specified) 300 m (984.25 ft)
• Individual minimum stated wire size is for electrical needs
• Clamp-type terminals accept two 14 AWG wires or one 12 AWG wire
• Terminal blocks accept two 12 AWG wires
• PTs and CTs use 10 AWG stranded wire
Note Wires with appropriate temperature ratings must be used, especially in applications where the internal cabinet ambient
temperature can exceed 60°C (140 °F).
It is standard practice to use shielded cable with control equipment. Shielding provides the following benefits:
• Generally, shielding protects a wire or combination of wires from its environment.
• Low-level signals may require shielding to prevent signal interference due to the capacitive coupling effect between two
sources of potential energy.
6.7.2 I/O Field Wiring Restrictions
Board Limitation
15 Ω maximum two-way cable resistance, cable length up to 300 m (984 ft)
TBAI
15 Ω maximum two-way cable resistance, cable length up to 300 m (984 ft)
STAI
15 Ω maximum two-way cable resistance, cable length up to 300 m (984 ft)
SAII
Driven devices should not exceed a resistance of 900 Ω and can be located up to 300 m (984 ft) from the control cabinet
TBAO
Driven devices should not exceed a resistance of 900 Ω and can be located up to 300 m (984 ft) from the control cabinet
STAO
CANopen cable limits are defined by the standard. GEH-6721_Vol_II provides and a table with baud rate to maximum distances
PCNO
Foundation Fieldbus standards for cabling apply
PFFA
15 Ω maximum two-way cable resistance, cable length up to 300 m (984 ft)
SHRA
GEH-6721_Vol_II provides a summary of Profibus cable requirements including a bus length vs. data rate table
PPRF
The eight RTDs can be located up to 300 meters (984 feet) from the distributed I/O cabinet with a maximum two-way cable
PRTD
resistance of 15 Ω
GEH-6721_Vol_II lists cable distance and maximum baud rate for the three supported communication standards
PSCA
Thermocouples can be located up to 300 meters (984 feet) from the turbine I/O panel with a maximum two-way cable resistance of
PTCC
450 Ω
Often sensors used with this input module impose their own cabling requirements
PVIB
Often sensors used with this input module impose their own cabling requirements
PAMC
For thermocouples- 450 Ω maximum two-way cable resistance, cable length up to 300 m (984 ft)
For analog inputs- 15 Ω maximum two-way cable resistance, cable length up to 300 m (984 ft)
PCLA
Other signals do not list a cable specification so the product level requirement applies
RS232 and RS485 standards are invoked for speed repeater output signals
PPRA
V3 383 TPRO and 388 SPRO for voltage sensing limits cable length up to 1,000 ft. of 18 AWG wiring
PPRO
GEH-6721_Vol_II provides cable distance and maximum baud rate for the three supported communication standards
PSCH
Installation Guidelines
Public Information
GEH-6721_Vol_I_BP System Guide 149