Answer: a) 0.948 b) 117.5µf
Explanation:
Given the load, a total of 2.4kw and 0.8pf
V= 120V, 60 Hz
P= 2.4 kw, cos θ= 80
P= S sin θ - (p/cos θ) sin θ
= P tan θ(cos^-1 (0.8)
=2.4 tan(36.87)= 1.8KVAR
S= 2.4 + j1. 8KVA
1 load absorbs 1.5 kW at 0.707 pf lagging
P= 1.5 kW, cos θ= 0.707 and θ=45 degree
Q= Ptan θ= tan 45°
Q=P=1.5kw
S1= 1.5 +1.5j KVA
S1 + S2= S
2.4+j1.8= 1.5+1.5j + S2
S2= 0.9 + 0.3j KVA
S2= 0.949= 18.43 °
Pf= cos(18.43°) = 0.948
b.) pf to 0.9, a capacitor is needed.
Pf = 0.9
Cos θ= 0.9
θ= 25.84 °
(WC) V^2= P (tan θ1 - tan θ2)
C= 2400 ( tan (36. 87°) - tan (25.84°)) /2 πf × 120^2
f=60, π=22/7
C= 117.5µf
Answer:
D.
Explanation:
In automated welding, defined as “welding with equipment that requires only occasional or no observation of the weld, and no manual adjustment of the equipment controls,” the welder's involvement is limited to activating the machine to initiate the welding cycle and observing the weld on an intermittent basis.
Answer:
The frequency that the sampling system will generate in its output is 70 Hz
Explanation:
Given;
F = 190 Hz
Fs = 120 Hz
Output Frequency = F - nFs
When n = 1
Output Frequency = 190 - 120 = 70 Hz
Therefore, if a system samples a sinusoid of frequency 190 Hz at a rate of 120 Hz and writes the sampled signal to its output without further modification, the frequency that the sampling system will generate in its output is 70 Hz
Answer:
1. Location of enemy ground troops - EARTH OBSERVING.
Using earth observing satellite imagery, the military can observe vast expanses of land and in so doing, find the location of enemy ground troops.
2. Routine reconnaissance of an unfamiliar climate - WEATHER
In other to find out more about the climate of an area, a weather satellite can be used to observe the areas and its changing weather patterns.
3. Analyze waterways in an unfamiliar location - NAVIGATION
Using navigation satellites, navigation conduits such as roads and waterways can be observed.
4. Provide warning of an attack - COMMUNICATION.
Communications satellites enable people to communicate over great distances and so can be used by the military to warn of an impending attack.
Answer:
Evaporator,Compressor,Condensor ,Expanding valve
Explanation:
Split air conditioning :
Split air conditioning means that, condensor unit or some time called outdoor unit is split from evaporator.It means that evaporator and condensor are placed at some distance.
The four component of split air conditioning system are as follows
1.Evaporator
It absorb heat from room and produces the cooling effect.
2.Compressor
It compresses the refrigerant which exits from evaporator.
3.Condensor
It rejects the heat and cool the evaporator.
4.Expanding valve
It allows to refrigerant to cool up to evaporator pressure.
