EFLOW EF-Series - Connecting Ground Wiring

Using the EF-Series Unit
2-16 Rev 2/01
The following connectors are provided on the Main Electronics Board:
♦ Battery Input – POWER, BAT
♦ Charge Input – POWER, CHG
♦ Auxiliary Radio Power – RADIO
♦ Flow Sensor – P/DP
♦ Discrete Output – DO
♦ Resistance Temperature Detector – RTD
♦ Operator Interface port – LOI
♦ Communications card connector – P3
The input terminal wiring is arranged on the lower edge of the Main Electronics Board. The terminal
designations are printed along the bottom of the circuit board as shown in Figure 2-1 on Page 2-9.
2.5.2 Connecting Ground Wiring
The EF-Series flow computer and related components must be connected to an earth ground. The
National Electrical Code (NEC) governs the ground wiring requirements for all line-powered devices.
Refer to Section 1 for further details.
There is a ground bar located inside the enclosure at the top right-hand side. This ground bus bar is
electrically bonded to the enclosure and provides screw compression terminals to connect shields from
I/O wiring, line-power earth ground, and other device earth grounds as needed.
An external lug on the bottom outside of the enclosure (refer to Figure 2-2) provides a place to connect
an earth ground to the enclosure. Although this ground lug is electrically connected to the ground bar
through the enclosure, it is recommended that a ground wire also be connected between the ground lug
and the ground bar.
It is recommended that 14 AWG wire be used for the ground wiring. Make sure the installation
has only one ground point to prevent creation of a ground loop circuit. A ground loop circuit could
cause erratic operation of the system.
The Main Electronics Board is electrically isolated from the enclosure; no earth ground connections to
the board should be made. However, the drain shields of I/O signal wiring (such as the RTD cable)
should be connected to earth ground at one end to minimize signal errors caused by EMI
(electromagnetic interference), RFI (radio frequency interference), and transients.
CAUTION
Do not connect the earth ground to any terminal on the Main Electronics Board.