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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 Current Characteristic Required element

AC DC

Yes Yes If the load is a relay or solenoid, there

is a time lag between the moment the

circuit is opened and the moment the

load is reset.

If the supply voltage is 24 or 48 V,

insert the surge protector in parallel

with the load. If the supply voltage is

100 to 200 V, insert the surge protector

between the contacts.

The capacitance of the capacitor must

be 1 to 0.5 µF per contact current of

1 A and resistance of the resistor must

be 0.5 to 1 Ω per contact voltage of 1 V.

These values, however, vary with the

load and the characteristics of the

relay. Decide these values from experi-

ments, and take into consideration that

the capacitance suppresses spark dis-

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.

CR method

Power

supply

Inductive

load