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DC-RELAYS AND INDUCTIVE LOADS

AC INPUT	POSSIBLE REASONS	TECHNICAL ASPECTS	DELCON SOLUTION
Relays/optos operate by them selves.	Capacitive leakage due to long signal wires and/or parallel lying signal and load cables.	100 m wire´s capacitance can be up to 10 nF. This generates relatively high voltage in the cable.	SLI ...CR
Relays/optos do not release.
Reason to failure is difficult to find due to unreliable status indication.	LED is glowing even the relay/opto is not on.	Operation and signal is not in synchrone. Capacitive leakage.
Indefinite operation of proxy	2 wire proxy with snubber in secondary	High leakage current + capacitive leakage	SLI ...CRP
Optos break suddenly.	High transients from field	Poor protection in primary	SLI ...CH

AC OUTPUT	POSSIBLE REASONS	TECHNICAL ASPECTS	DELCON SOLUTION
Relays break and must be changed.	Inductive load	Mechanical lifetime of a relay is 10.000.000 cycles. Electrical life time is much less, please see the diagrams	SLO ...TR
	High switching frequency
Opto doesn´t release.	Capacitive leakage between poles	Signal lines > 100 m long
Malfunction of proxys	Long or parallel cables	Proxy´s leakage typically 0,5...3,5 mA	SLO P...TR

DC OUTPUT	POSSIBLE REASONS	TECHNICAL ASPECTS	DELCON SOLUTION
	High switching frequency with resistive load	Check number of cycles from relays diagram with real load	SLO ...CR, 3 A SLO ...CRX, 10 A
Relays wear out fast.	Switching-off inductive load	Check number of cycles. Select right component to extinguish the spark. Note that a diode leghtens the off-delay!	SLO ...CRA SLO ...CRA4 (SLO ...CR, L/R < 5ms) (SLO ...CRX only with clamb diode in the poles of the load)
Relays wear out fast and/or operate unreliably.	High DC voltages	Typically 110 V or 220 V	SLO ...CRA, 1,8 A up to 220 VDC SLO ...CRA4, 4 A up to 220 VDC

DC INPUT	POSSIBLE REASONS	TECHNICAL ASPECTS	DELCON SOLUTION
Problem to find out trouble maker	Unreliable signal condition	Highly disturbed environment	SLI ...CR

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