While selecting LED driver, sometimes may find that LED driver constant current output less than specified value and then gradually reach it after LED lamps emit heat. The reason is the number of LED lamp in series is lager than specified value. Each LED lamp forward Vf typical value is usually 3.2V while working, and 3.6V when in low temperature. Hence customer should use 3.6V if LED lamps work in Low temperature area.

Monopole PFC LED driver may strikes sparks at poor connection, this leads to high frequencey power onoff status and damages LED driver finally.

Common damage type:

1.blowout

2.rectifier bridge short circuit owing to high frequencey power onoff heating

3.MOSFET overheating owing to high frequencey power onoff This kind of products is unsuited working in high frequencey power onoff status, therefore input AC wire should be well connected to ensure LED driver working in right status.

Power factor PF is highly related to actual power, usually ,it is index of rated input power and should not drift from rated power obviously. Power factor PF concerns not only input power but also input voltage.

Follwing relationship is always established:

1.The lower the input voltage, the higher the PF value, vice versa.

2.The smaller the input power, the lower the PF value, vice versa.

3.Power factor is high when ohmic load and low when LED lamp load. Generally, it’s recommended to use 80% above actual power of selected LED driver, PF value can meet Energy Star standard.