Emerson Process Management ControlWave XFC - Manual (Page 67)

CI-ControlWave XFC Installation & Operation / 2-25
wire, tin the bare end with solder to prevent flattening and improve conductivity. Allow
some slack in the wires when making connections. The slack makes the connections more
manageable and helps to minimize mechanical strain on the terminal blocks.
2.3.6.1 Bulk Power Supply Current Requirements
ControlWave XFC electronic flow computers are designed to operate from a +6Vdc to
+30Vdc Bulk Power input. The maximum current required for a particular ControlWave
XFC is 5mA, plus 4mA for each active communication port (regardless of the bulk supply
voltage), plus any current (up to 20mA) used to supply the AO. This current consumption is
based on a standard Gas Flow Computer application load.
2.3.6.2 Power Wiring
One Bulk DC supply can be connected to the ControlWave XFC. The Bulk DC supply
(+6Vdc to +30Vdc) connects to Terminal Block J6 on the Terminal Plate and is converted,
regulated and filtered to produce +3.3Vdc. The I/O Board circuit is fused at .375A (F1).
Terminal Plate Connector J6 provides 2 input connections for bulk power:
J6-1 = (+VIN) (+6.0Vdc to +30.0Vdc)
J6-2 = (-VIN) (Supply Ground)
Figure 2-16 - Terminal Plate Connector (J6) - Primary Power Wiring
2.3.6.3 ControlWave XFC System Grounding
ControlWave XFC Cases are optionally provided with a Ground Lug that accommodates
up to a #4 AWG wire size. A ground wire should be run between the Case’s Ground Lug (see
Figure 2-2) and a known good Earth Ground. The following considerations are provided for
the installation of ControlWave XFC system grounds (see S1400CW):
• Chassis Ground Lug to Earth Ground wire size should be #4 AWG. It is recommended
that stranded copper wire is used and that the length should be as short as possible.
• This ground wire should be clamped or brazed to the Ground Bed Conductor (that is
typically a stranded copper AWG 0000 cable installed vertically or horizontally).
• The wire ends should be tinned with solder prior to insertion into the Chassis Ground
Lug. Note: Use a high wattage Soldering Iron.
• The ground wire should be run such that any routing bend in the cable has a minimum
radius of 12-inches below ground and 8-inches above ground.
2.3.7 Operation of the Lithium Backup Coin-cell Battery
CPU Boards are equipped with a Coin-cell Socket (BT1) that accommodates a 3.0V, 300
mA-hr lithium coin cell. A supervisory circuit on the CPU Board is used to switch to battery
power when the regulated 3.3Vdc VCC falls out of specification. The CPU Board switches
the battery voltage to the VBAT3.3 hardware signal, which provides backup power for the
real-time clock (RTC) and the system SRAM on the CPU Module.