Meaning of Full Load Amperes (FLA)

[Mark_Djorn]

Hi All,

I have a FCU rated at 1.1 kW (3 speeds) but stating 2.8 A (FLA).

Can anyone explain me what FLA is and why 3.8 A? If I make my maths: 1100 W / 230 V is 4 78 A.

Not sure what I am doing wrong. Thank you.
Mark

 

[sinewove]

There is the calcs that I pinched from a site.

Motor FLC calculator | Motor Full load current calculator

The motor full load current forms the basis for the selection of switchgear. Here is a motor FLC calculator that calculates the motor full load current.

www.electricalclassroom.com

View attachment 93412

Is that a greek n for efficiency,thought n was used for speed.
S

 

[pc1966]

Is that a greek n for efficiency,thought n was used for speed.
S

Yes, the lower case Greek 'eta' is typically used for efficiency.

But as you say 'n' is common for speed (I suspect from number of revs / minute) or in some cases Greek lower case omega (usually for angular velocity in radians/sec).

 

[Lucien Nunes]

There is only one motor, the fan motor.
By 'Motor kW' it means the maximum rated mechanical output power of the motor, as decided by the motor manufacturer.
By 'Fan absorbed power' it means how much mechanical power the impeller absorbs from the motor shaft, as decided by the FCU manufacturer.

So the motor is capable of 1.5kW but the impeller only applies 1.16kW of load to it, leaving a margin so that the motor is not worked to its maximum. However, the full load current is specified for the motor working at 1.5kW mechanical output (P2) and it is a reasonable figure given the rated 415V supply voltage and 83% efficiency (I've taken the power factor as 0.75):
1500 / 0.83 / 0.75 / 415 / sqrt(3) = 3.35A
Which compares well to the stated 3.42A.

With the fan impeller taking only 1.16kW instead of 1.5kW the actual line current will be lower, although not by the factor 1.16/1.5 because only the in-phase current will be reduced, not the magnetising current (and the pf will be lower).