Grounding Electrode; Ground Bus - Toshiba V Series User Manual

Chapter 3 Installation & Wiring
3.4.2

Grounding Electrode

3.4.3

Ground Bus

3
54
Prepare grounding electrodes exclusive for the L3 controller. Ground resistance must be
100 Ω or less (equivalent to Class-D grounding).
The following paragraphs describe the ground bus.
INSTRUCTIONS
2
• Use 8 mm (AWG #8) or thicker cable for ground bus.
Absolutely do not connect equipment other than L3 controller (model 3000) to the ground
bus.
Connection of multiple L3 controllers in the same control room
to the ground bus
To connect multiple L3 controllers in the same control room to the same ground bus, use
bolt connectors or attach a lead-in terminal to the ground bus, as shown in figure 3-12.
Do not connect one ground bus sequentially to multiple L3 controllers. The grounding
conductors must not form a loop.
Connect the ground terminal of each L3 controller and the common ground bus, using 8
2
mm (AWG #8) grounding conductor.
L3 controller L3 controller
console console
Bolt connector
Figure 3-12 Example Connection of Grounding Conductors to Ground Bus
Grounding of main unit and expansion units
Connect the FG terminal of the power supply module to the base unit fixing screw, and to
the drop ground bus (frame ground), via the shortest route, using 2 mm
Carry out Class-D grounding exclusive for the L3 controller, with the grounding conductor
isolated from that of high-power system circuits.
• Line filter ground (LG) terminal
The LG terminal is the neutral point of line filter for the primary power supply. Grounding
of the LG terminal is effective in reducing the influence of common mode noise
transmitted through the power supply line.
Therefore, connect the LG terminal and the drop ground bus using 2 mm
cable. However, if single-side grounding is used for the power supply, leak current may
flow from the LG terminal to the grounding conductor, causing a problem. In such a case,
install an insulating transformer in the power supply unit, or open the LG terminal. Also
open the LG terminal when the basic or expansion unit is mounted as insulated.
Avoid connecting LG and FG terminals without grounding them.
L3 controller L3 controller
console console
2
8mm
22mm
Grounding electrode with
resistance of 100 Ω or
less
model 3000 Loop Controller L3 User's Manual - Basic Hardware -
L3 controller L3 controller L3 controller
console console console
2
8mm
Lead-in terminal
2
2
22mm
Grounding electrode with
resistance of 100 Ω or
less
2
or thicker cable.
2
or thicker