Watlow CPC400 Bedienungsanleitung PDF herunterladen (Seite 36)

Chapter 2: Installation CPC400 Series User’s Guide

22 Watlow Anafaze Doc. 0600-2900-2000

Avoiding Noise

To avoid or eliminate most RFI/EMI noise problems:

• Connect the CPC400 case to earth ground. The

CPC400 system includes noise suppression circuitry.

This circuitry requires proper grounding.

• Separate the 120VÅ (ac) and higher power leads from

the low-level input and output leads connected to the

CPC400 series controller. Do not run the digital I/O or

control output leads in bundles with ac wires.

• Where possible, use solid-state relays (SSRs) instead

of electromechanical relays. If you must use electro-

mechanical relays, avoid mounting them in the same

panel as the CPC400 series equipment.

• If you must use electromechanical relays and you

must place them in a panel with CPC400 series equip-

ment, use a 0.01 microfarad capacitor rated at 1000V

(ac) (or higher) in series with a 47 Ω, 0.5 watt resistor

across the normally-open contacts of the relay load.

This is known as a snubber network and can reduce

the amount of electrical noise.

• You can use other voltage suppression devices, but

they are not usually required. For instance, you can

place a metal oxide varistor (MOV) rated at 130VÅ (ac)

for 120VÅ (ac) control circuits across the load, which

limits the peak ac voltage to about 180VÅ (ac) (Watlow

Anafaze part number 26-130210-00). You can also

place a transorb (back-to-back zener diodes) across the

digital output, which limits the digital output voltage.

Additional Recommendations for a Noise Immune System

We strongly recommended the following:

• Isolate outputs through solid-state relays, where pos-

sible.

• Isolate digital inputs from ground through solid-state

relays. If this is not possible, then make sure the digi-

tal input is the only connection to earth ground other

than the chassis ground.

1 2 ... 31 32 33 34 35 36 37 38 39 40 41 ... 229 230

Keine Kommentare

Watlow CPC400 Bedienungsanleitung Seite 36