A 35 kVA transformer supplies a load of 12 kW at a power factor of 0.45 lagging.
Find the percentage of full load the transformer is carrying. If additional unity power
factor loads are to be served with the same transformer, how many kW may be added
before the transformer is at full load
1. KVA*cosA = 12 KW,
KVA*0.45 = 12,
KVA = 26.7. = KVA used.
%F.L. = (26.7/35) * 100% = 76.3.
2. P = (35-26.7)cosA,
P = 8.3*1 = 8.3 KW = Amt of unity P.F.
Load that can be added.
Alternate Method:
1. %F.L. = (12/(35*0.45) * 100% = 76.2
2. 12KW/0.45 + P/1 = 35 KVA,
26.7 + P = 35,
P = 35 - 26.7 = 8.3 KW. = Unity P.F.
Load that can be added.
To find the percentage of full load the transformer is carrying, we need to first calculate the actual load in kVA.
Given:
Transformer rating = 35 kVA
Load power = 12 kW
Power factor = 0.45 lagging
Since power (P) = apparent power (S) * power factor (PF), we can calculate the apparent power as follows:
Apparent Power (S) = Load Power (P) / Power Factor (PF)
S = 12 kW / 0.45
S = 26.67 kVA
Now we can find the percentage of full load the transformer is carrying:
Percentage of Full Load = (Actual Load / Transformer Rating) * 100
Percentage of Full Load = (26.67 kVA / 35 kVA) * 100
Percentage of Full Load ≈ 76.19%
To calculate the additional unity power factor loads that can be served with the same transformer before it reaches full load, we need to subtract the current load power from the transformer rating.
Remaining Load Power = Transformer Rating - Load Power
Remaining Load Power = 35 kVA - 12 kW
Remaining Load Power = 23 kW
Therefore, you may add up to 23 kW of additional unity power factor loads before the transformer reaches full load.