16
3.2.5 Module installation
(1) Installing modules contiguously
In Q2AS series programmable controllers, the left side of each I/O module is
left open. When installing an I/O module to the base, do not make any open
slots between any two modules. If there is an open slot on the left side of a
module with 100/200 VAC rating, the printed board which contains the
hazardous voltage circuit becomes bare. When it is unavoidable to make an
open slot, be sure to install the blank module (A1SG60).
3.2.6 Grounding
There are two kinds of grounding terminals as shown below. Either grounding
terminal must be used grounded.
Be sure to ground the protective grounding for the safety reasons.
Protective grounding
: Maintains the safety of the programmable
controller and improves the noise resistance.
Functional grounding
: Improves the noise resistance.
3.2.7 External wiring
(1) Module power supply and external power supply
For the remote module which requires 24VDC as module power supply, the
5/12/24/48VDC I/O module, and the intelligent function module (special
function module) which requires the external power supply, use the
5/12/24/48VDC circuit which is doubly insulated from the hazardous voltage
circuit or use the power supply whose insulation is reinforced.
(2) External devices
When a device with a hazardous voltage circuit is externally connected to the
programmable controller, use a model whose circuit section of the interface to
the programmable controller is intensively insulated from the hazardous
voltage circuit.
(3) Intensive insulation
Intensive insulation refers to the insulation with the dielectric withstand
voltage shown in Table 1.
Table 1: Intensive Insulation Withstand Voltage
(Installation Category II, source: IEC664)
Rated voltage of hazardous voltage area
Surge withstand voltage (1.2/50 µs)
150 VAC or below
2500 V
300 VAC or below
4000 V
