Scenario

When supplied with the appropriate voltage, the relay actuates or switches, but no current flows between the contact points.

Issue

The cause of this scenario can be due to several different issues, listed below.

1. Damage to internal components due to shock: If the relay has been dropped or otherwise exposed to physical shock, the internal components may have moved or become deformed, which makes the connection between the contact points unstable.
2. Relay is nearing end-of-life: Switching loads causes erosion of the contact points. When a relay nears its end-of-life, it may still operate but the current flow can become unstable.
3. Minimum load switching leading to loose contact points: If a relay with silver (or silver-alloy) contacts is used for minimum load switching, the switching activity can create insulating material such as sulphur to gradually appear on the contacts, which can result in an unstable connection.
4. Foreign body between contact points: If dusts, powders, wire debris or other coating materials become stuck between the contact points, it can create an unstable connection.
5. Inductive load switching leading to loose contacts: Switching an inductive load using solenoids or valves can produce an arc discharge, which itself produces carbon. An accumulation of carbon on the contact points can lead to an unstable connection.

Solution

In order, the solutions to the above issues are as follows.

1. Damage to internal components due to shock: Replace the relay. Handle the new relay with care to avoid physical shock.
2. Relay is nearing end-of-life: Replace the relay.
3. Minimum load switching leading to loose contact points: Replace the relay with a model that uses gold-plated cross-bar twin or twin contacts.
4. Foreign body between contact points: Replace the relay. Ensure that the new relay is installed in an IP-rated case to avoid future foreign body penetration.
5. Inductive load switching leading to loose contacts: Install surge protection suitable for the applied inductive load.