ABB AX418 User Manual

Also see for AX418: Manual User guide User guide

ABB AX418 User Manual Manual pdf 45 page image

436 INSTALLATION…Fig. 6.6 Relay Contact ProtectionNC C NOExternalDC Supply+ –Relay ContactsLoadDiodeNC C NOExternalAC SupplyL NRelay ContactsCRLoadA – AC Applications B – DC Applications…6.3 Electrical Connections6.3.1 Relay Contact Protection and Interference Suppression – Fig. 6.6If the relays are used to switch loads on and off, the relay contacts can become eroded due to arcing. Arcing also generates radiofrequency interference (RFI) which can result in analyzer malfunctions and incorrect readings. To minimize the effects of RFI, arcsuppression components are required; resistor/capacitor networks for AC applications or diodes for DC applications. Thesecomponents must be connected across the load – see Fig 6.6.For AC applications the value of the resistor/capacitor network depends on the load current and inductance that is switched. Initially,fit a 100R/0.022F RC suppressor unit (part no. B9303) as shown in Fig. 6.6A. If the analyzer malfunctions (locks up, display goesblank, resets etc.) the value of the RC network is too low for suppression and an alternative value must be used. If the correct valuecannot be obtained, contact the manufacturer of the switched device for details on the RC unit required.For DC applications fit a diode as shown in Fig. 6.6B. For general applications use an IN5406 type (600V peak inverse voltage at 3A).Note. For reliable switching the minimum voltage must be greater than 12V and the minimum current greater than 100mA.