Omron FQM1-MMA21 Relay Output Noise Reduction Methods, Countermeasures, Countermeasure Examples

Conformance to EC Directives 4

4-5 Relay Output Noise Reduction Methods

The FQM1-series Flexible Motion Controller conforms to the Common Emis- sion Standards (EN61000-6-4) of the EMC Directives. However, noise gener- ated by relay output switching may not satisfy these Standards. In such a case, a noise filter must be connected to the load side or other appropriate countermeasures must be provided external to the Motion Controller.

Countermeasures taken to satisfy the standards vary depending on the devices on the load side, wiring, configuration of machines, etc. Following are examples of countermeasures for reducing the generated noise.

Countermeasures

(Refer to EN61000-6-4 for more details.)

Countermeasures are not required if the frequency of load switching for the whole system with the Motion Controller included is less than 5 times per minute.

Countermeasures are required if the frequency of load switching for the whole system with the Motion Controller included is more than 5 times per minute.

Countermeasure Examples

When switching an inductive load, connect an surge protector, diodes, etc., in parallel with the load or contact as shown below.

Circuit

CR method

C

Power R supply

Inductive load

Current		Characteristic	Required element
AC	DC
Yes	Yes	If the load is a relay or solenoid, there	The capacitance of the capacitor must
		is a time lag between the moment the	be 1 to 0.5 ∝F per contact current of
		circuit is opened and the moment the	1 A and resistance of the resistor must
		load is reset.	be 0.5 to 1 Ω per contact voltage of 1 V.
		If the supply voltage is 24 or 48 V,	These values, however, vary with the
			load and the characteristics of the
		insert the surge protector in parallel
			relay. Decide these values from experi-
		with the load. If the supply voltage is
			ments, and take into consideration that
		100 to 200 V, insert the surge protector
			the capacitance suppresses spark dis-
		between the contacts.
			charge when the contacts are sepa-
			rated and the resistance limits the
			current that flows into the load when
			the circuit is closed again.
			The dielectric strength of the capacitor
			must be 200 to 300 V. If the circuit is an
			AC circuit, use a capacitor with no
			polarity.

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