Chapter 3. INSTALLATION AND MOUNTING

Sources of electrical interference and countermeasures

•The following list notes common sources of electrical interference.

(1)Relays and contacts

(2)Solenoid coils and valves

(3)Power lines (especially those carrying more than 90V AC)

(4)Inductive loads

(5)Inverters

(6)Motor rectifiers

(7)Phase angle control SCR

(8)Wireless communications equipment

(9)Welding machines

(10)High voltage ignition devices

•If the source of noise cannot be removed, take the following measures. •Use a CR filter to suppress fast-rising noise.

Recommended CR filter : No. 81446365-001

•Use a varistor to suppress high-amplitude interference. Recommended varistors : No. 81446366-001(for 110 to 120V)

81446367-001(for 200 to 240V)

Handling Precautions

Varistors must be handled carefully as they become defective if they are short-circuited.

Dust proof cover

Use the soft dust proof cover when the DCP552 is used in locations where there is a lot of dust.

See Section “Soft dust-proof cover set (optional)” on page 11-8 for details.

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Honeywell DCP552 Mark II user manual Sources of electrical interference and countermeasures, Dust proof cover