Various phenomena of poor relays

Q: MY/LY series relays have abnormal noise after being powered on

A:

1. Fault phenomenon: There is an abnormal noise after the relay is powered on.

2. Fault cause:

(1) The relay coil of the DC coil is subjected to AC voltage, causing the movable iron plate to vibrate repeatedly and produce abnormal sounds.

(2) The voltage at the coil is unstable.

(3) Oxidative corrosion or foreign objects on the contact surface.

(4) There is mechanical poor contact (terminal deviation, detachment).

(5) The relay has reached the specified durability frequency.

(6) The usage environment includes vibration, shock, magnetic field, etc.

Q: MY/LY series relay output contacts are always conductive and cannot be disconnected

A:

1. Fault phenomenon: The relay is not powered on, but the output contact is always conductive and cannot be disconnected.

2. Fault cause:

(1) The load capacity of the relay connection exceeds the contact capacity of the relay.

(2) The switching frequency is too high, exceeding the rated operating frequency of the relay.

(3) The relay has reached the specified durability frequency.

(4) When switching the load, the arc discharge between the contacts is twisted by the external magnetic field or the magnetic field generated by the operating coil, reaching the coil terminals and generating flashover.

Q: MY/LY series relays do not operate
A:

1. Fault phenomenon: After the relay is powered on, the contact does not act.

2. Fault cause:

(1) Excessive voltage is applied to the relay coil, causing the coil to break.

(2) Insufficient voltage is applied to the relay coil, resulting in the relay not acting.

① The applied voltage of the coil has not reached the minimum operating voltage (80% Max).

② Due to the operation of large machines or the use of long-distance wiring, the circuit voltage may decrease and the minimum operating voltage may not be reached.

③ Due to the high temperature used on site, the resistance value of the relay coil increases, causing an increase in the action voltage required to drive the relay to operate, resulting in the originally applied rated voltage being insufficient to drive the relay to operate.

(3) The voltage polarity of the built-in diode type relay coil is reversed, causing the built-in diode to short-circuit and breakdown, making the relay unable to operate, as shown in the figure:

Q: The contact resistance of MY/LY series relays is too high/not conducting

A:

1. Fault phenomenon: After the relay is powered on, the contact acts, but the contact resistance is too high/not conducting.

2. Fault cause:

(1) Foreign objects (dust, forming powder, coatings, wire chips, insulation sheath, carbon, etc.) are mixed between the contacts.

(2) Output load overload, overcurrent, or long-term storage or use in high-temperature and humid environments, resulting in the formation of oxide film or vulcanized coating on the contact surface, resulting in poor contact, as shown in the figure:

(3) Terminal misalignment and contact misalignment caused by vibration, impact, or external magnetic field, as shown in the figure:

(4) Poor contact caused by contact following (contact follower) and loss of contact pressure caused by contact consumption.

Q: MY/LY series relays burned out

A:

1. Fault phenomenon: The relay is internally burnt out.

2. Fault cause:

(1) Applying DC voltage to the relay coil of the AC coil may cause heating of the coil, which may cause burnout.

(2) The output load of the relay is too large.

(3) Added on the online circle