Installation instructions for EMC

When constructing a control cabinet where the PC system will be installed, the following instructions must be followed.

(1) Use a conductive control cabinet.

(2) When attaching the control cabinet's top plate or base plate, mask painting and weld so that good surface contact can be made between the cabinet and plate.

(3) To ensure good electrical contact with the control cabinet, mask the paint on the installation bolts of the inner plate in the control cabinet so that contact between surfaces can be ensured over the widest possible area.

(4) Earth the control cabinet with a thick wire so that a low impedance connection to ground can be ensured even at high frequencies. (22mm² wire or thicker is recommended.)

(5) Holes made in the control cabinet must be 10cm (3.94in.) diameter or less.

If the holes are 10cm (3.94in.) or larger, radio frequency noise may be emitted.

(6) Connect the door of cabinet to the main body with flat braided wires at as many points as possible so that a low impedance can be ensured even at high frequencies.

3.1.2.2 Connection of power and ground wires

Ground and power supply wires for the PC system must be connected as described below.

(1) Provide an earthing point near the power supply module. Earth the power supply's LG and FG terminals (LG : Line Ground, FG : Frame Ground) with the thickest and shortest wire possible. (The wire length must be 30cm (11.18in.) or shorter.) The LG and FG terminals function is to pass the noise generated in the PC system to the ground, so an impedance that is as low as possible must be ensured. As the wires are used to relieve the noise, the wire itself carries a large noise content and thus short wiring means that the wire is prevented from acting as an antenna.

Note) A long conductor will become a more efficient antenna at high frequency.

(2) The earth wire led from the earthing point must be twisted with the power supply wires. By twisting with the earthing wire, noise flowing from the power supply wires can be relieved to the earthing. However, if a filter is installed on the power supply wires, the wires and the earthing wire may not need to be twisted.

(3) Except for A1S61PN and A1S62PN, short between FG and LG terminals by a short jumper wire.

3.1.2.3 Cables

The cables led from the control cabinet contain a high frequency noise element and outside the control panel these cables act as antennae and radiate noise.

The cables connected to input/output modules or special modules which leave the control panel should always be shielded cables.

Mounting of a ferrite core on the cables is not required (excluding some models) but if a ferrite core is mounted, the noise radiated through the cable can be suppressed further.

Use of a shielded cable is also effective for increasing the noise immunity level.

The PC system's input/output and special function module provide a noise immunity level of equivalent to that stated in IEC801-4 : 2kV when a shielded cable is used. If a shielded cable is not used or if the shield earthing treatment is not suitable even when used (See Section 3.1.2.4), the noise immunity level is less than 2kV.

Note) prEN50082-2 specifies the noise resistance level based on the signal wire application.

Signals involved in process control : 2kV Signals not involved in process control : 1kV

The meaning of "involved in process control" is not defined in prEN50082-2.

However, when the purposes of the EMC Directive are considered, the signals that could cause personal injury or risks in the facility if a malfunction occurs should be defined as "signals involved in process control". Thus, it is assumed that a high noise immunity level is required.

3.1.2.4 Shield earthing

When the shield of the shielded cable is earthed to the cabinet body, please ensure that the shield contact with the body is over a large surface area. If the cabinet body is painted it will be necessary to remove paint from the contact area.

All fastenings must be metallic and the shield and earthing contact must be made over the largest available surface area. If the contact surfaces are too uneven for optimal contact to be made either use washers to correct for surface inconsistencies or use an abrasive to level the surfaces. The following diagrams show examples of how to provide good surface contact of shield earthing by use of a cable clamp.

Shield section

Screw

Shielded cable Paint mask

Clamp fitting

(a) Peel the cable insulation off and expose the

shield section.

(b) Sandwich the exposed shield section with the and earth to the control cabinet over a wide area.

Note) The method of earthing by soldering a wire onto the shield section of the shielded cable as shown below is not recommended. The high frequency impedance will increase and the shield will be ineffective.

Shielded cable Wire

Crimp terminal

3.1.2.5 MELSECNET/II module

The following requirements apply to A1SJ71AR21, A1SJ71BR11, AnNCPUR21, AnACPUR21.

(1) Always use a triaxial cable for the module. The radiated noise in the band of 30MHz or higher can be suppressed by using a triax cable. Earth the outer shield by the method described in Section 3.1.2.4.

Earth this section

(2) Always mount a ferrite core onto the triaxial cable. Mount the ferrite core near the control cabinet outlet of each cable. Use of the TDK ZCAT3035 ferrite core is recommended.

3.1.2.6 Ethernet module

(1) Always earth the AUI cable connected to the A1SJ71E71-B5. The AUI is a shielded cable so remove the outer insulation and connect to earth the exposed shield section using as wide a surface area as possible in the manner shown below.

Shield AUI cable

(2) Always use a triaxial cable for the coaxial cable connected to the A1SJ71E71-B2. The earthing precautions are the same as Section 3.1.2.5.

(3) For A1SJ71E71-B2/B5, always mount a ferrite core in addition to items (1) and (2) above. Use of the TDK ZCAT3035 ferrite core is recommended.

3.1.2.7 Positioning Modules

(1) When wiring with a 2m (6.6ft.) or less cable

Ground the shield section of the external wiring cable with the cable clamp.

(Ground the shield at the closest location to the A1SD75 external wiring connector.)

Wire the external wiring cable to the drive unit and external device with the shortest distance.

Install the drive unit in the same panel.

Power supply module CPU module A1SD75 module

Drive unit External wiring connector

External wiring cable (within 2 m (6.56 ft.)) Cable clamp

(2) When wiring with cable that exceeds 2m (6.6ft.), but is 10m (32.8ft.) or less Ground the shield section of the external wiring cable with the cable clamp.

(Ground the shield at the closest location to the AISD75 external wiring connector.)

Install a ferrite core.

Wire the external wiring cable to the drive unit and external device with the shortest distance.

Power supply module CPU module A1SD75 module

Drive unit External wiring connector

Ferrite core

External wiring cable (2 m to 10 m (6.56 ft. to 32.81 ft.)) Cable clamp

(3) Ferrite core and cable clamp types and required quantities

(a) Cable clamp

Type : AD75CK (Mitsubishi Electric) (b) Ferrite core

Type : ZCAT3035-1330 (TDK ferrite core) (c) Required quantity

Required Qty Cable length Prepared part

1 axis 2 axes 3 axes

Within 2m (6.6 t.) AD75CK 1 1 1

AD75CK 1 1 1

2m (6.6ft.) to 10m (32.8ft.)

ZCAT3035-1330 1 2 3

3.1.2.8 I/O and other communication cables

Always earth the shield section of the I/O signal cables and other communication cables (RS-232-C, RS-422, etc.) in the same manner as described in Section 3.1.2.4 if the cables go outside of the control cabinet.

3.1.2.9 Power supply module

The precautions required for each power supply module are described below.

Always observe the items noted as precautions.

Model Precautions A1S61P

A1S62P A1S63P ^*1

Always mount one of the filters listed in Section 3.1.2.10 to the incoming power supply lines.

A1S61PEU

A1S62PEU None A1S61PN

A1S62PN Make sure to short and ground the LG and FG terminals.^*2 A1SJCPU-S3

A1SJHCPU A1SJHCPU-S8

Always ground the LG and FG terminals after short-circuiting them.

*1 If a sufficient filter circuitry is built into a 24VDC external power supply module, the noise generated by A1S63P will be absorbed by that filter circuit, so a line filter may not be required.

Filtering circuitry of version F or later of A1S63P is improved so that a external line filter is not required.

*2 To ensure the compliance with CE (EN6111-21/A11), make sure to short the LG and FG terminals using a wire of 6 to 7cm.

3.1.2.10 Ferrite core

A ferrite core is effective for reducing noise in the band of 30MHz to 100MHz.

Mounting of a ferrite core is not necessary except for some particular models described in Section 3.1.2.5 and 3.1.2.6. However if further attenution of noise is necessary, mounting of a ferrite core on cables which radiate noise is recommended. When a ferrite core is mounted, mount the ferrite core just before the point where the cable goes outside of the cabinet. The ferrite will not be effective if the mounting position is not adequate.

Ferrite

core Ferrite

core

Noise Noise

(a) When there is a distance from the cable exit hole, the noise will jump over the ferrite, thus the effect will be halved.

(b) When mounted by the cable exit hole, the noise will not jump over the ferrite.

3.1.2.11 Noise filter (power supply line filter)

The noise filter (power supply line filter) is a device effective to reduce conducted noise. Except for some particular models described in Section 3.1.2.8, installation of a noise filter onto the power supply lines is not necessary. However conducted noise can be reduced if it is installed. (The noise filter is generally effective for reducing conducted noise in the band of 10MHz or less.) Usage of the following filters is recommended.

Model name FN343-3/01 FN660-6/06 ZHC2203-11

Manufacturer SCHAFFNER SCHAFFNER TDK

Rated current 3A 6A 3A

Rated voltage 250V

The precautions required when installing a noise filter are described below.

(1) Do not bundle the wires on the input side and output side of the noise filter. When bundled, the output side noise will be induced into the input side wires from which the noise was filtered.

Filter

Induction

Output side (device side) Input side

(power supply side)

Filter

Output side (device side) Input side

(power supply side)

(a) The noise will be included when the input and output wires are bundled.

(b) Separate and lay the input and output wires.

(2) Earth the noise filter earthing terminal to the control cabinet with the shortest wire possible (approx. 10cm (3.94 in.)).

3.2 Requirements for conpliance with the Low Voltage Directive (73/23/EEC) and