How do you determine the primary fuse size?

How do you determine the primary fuse size?

The primary fuses are sized as a % over the primary current in amps according to the chart below when secondary fusing is not used. Example. You have a 2KVA (2000 VA) transformer and your primary voltage is 460VAC and your secondary voltage is 120VAC. Primary Amps = VA/VAC = 2000/460 = 4.35 amps.

How do you determine the size of a transformer fuse?

A. Fuse = I*167% next size smaller if secondary current is less than 9 amp. Fuse = I*125% next size higher if secondary current is 9 amp. or higher. Fuse = I*167% next size smaller if primary current is less than 9 amp.

How do you measure a transformer disconnect switch?

Size the Secondary Side of the Transformer. Using the example numbers: Isecondary = (20 x 1000)/240= 20,000/240 = 83.3 amps. Note: If you had a 3-phase transformer, the formula would be Isecondary = KVA x 1000/(Vsecondary x 1.732).

How do you size a circuit breaker for a transformer?

For Primary Side:

1. Transformer Primary Current (Ip) =52.49Amp and impedance is 5%
2. As per above table in not supervised condition Size of Circuit Breaker= 600% of Primary Current.
3. Size of Circuit Breaker = 52.49 x 600% =315Amp.

What size breaker Do I need to feed a 75 kVA transformer?

The rated current of the transformer can be used as the basis for a breaker. The rated current of a 3 phase, 75 kva transformer is 112 Amps, which is 25% of the rated current of a 125 Amp breaker.

What size transformer do I need for a 200 amp service?

For a 200 A at 120 V single-phase service, the apparent power is 48 kVA. A 50 kVA transformer won’t be installed by the utility. Standard sizes of single phase transformers are 5, 10, 15, 25, 37.5, 50, 75, 100, and so on.

How many amps is a 45kva transformer good for?

Three Phase Transformer

KVA	208V	240V
45	125	108
50	139	120
60	167	145
75	208	181

Does a 200 amp 3 phase service equal a total of 600 amps?

Originally Answered: Does a 200 amp 3 phase service equal a total of 600 amps? No, because each one of the three phase wires is supplying amperage for only one third of the time. The power rotates very fast between those three wires, 60 times per second, so that enables the wires to be much smaller than normal.

How do you size a transformer panel?

Calculate an example as follows. A 120-volt motor has a load amperage of 5 amps. Multiply 120 volts times 5 amps this equals 600VA now lets multiply the 125 percent start factor. Take 600 times 1.25 this equals 720VA and most transformers are sized by a factor of 25VA or 50VA.

How do you size a transformer for a load?

How to Size a Transformer

1. Transformer size is determined by the kVA of the load.
2. Load voltage, or secondary voltage, is the voltage needed to operate the load.
3. Line voltage, or primary voltage, is the voltage from the source.
4. Single-Phase has two lines of AC power.

How do I choose a power supply for a transformer?

Input & Output Voltage(s), Frequency, Current. To select the proper transformer, determine the input and output voltages, frequency and current. The faster the voltage changes, the higher the frequency. The higher the current, the more heat is produced. Other equations apply.

Can a transformer convert AC to DC?

A transformer is not designed to convert AC to DC or DC to AC. The transformer can step-up or step -down current. A transformer that increases the voltage from the primary to secondary is called a step-up transformer.

How do you calculate the power of a transformer?

Input and output power

1. Electrical power is calculated by multiplying voltage (in volts) by current (in amps).
2. If a transformer is 100% efficient, then the input power will equal the output power.
3. V P is input (primary) voltage.
4. I p is input (primary) current.
5. V s is output (secondary) voltage.

How many amps is a 30 kVA transformer good for?

How many amps is a 30 kva transformer?

KVA	208V	240V
25	69.5	60.2
30	83.4	72.3
37.5	104	90.3
45	125	108

What size breaker do I need for a 30 kVA transformer?

The 1.732 accounts for the 3-phase configuration. Find the circuit breaker size for the primary side of the transformer by multiplying Iprimary by 1.25….How many amps can a 25 kva transformer handle?

KVA	208V	240V
25	69.5	60.2
30	83.4	72.3
37.5	104	90.3

How many amps is a 1000 kVA transformer good for?

Three Phase Transformers, Full Load Amperes (FLC)
KVA	208V	600V
500	1387	481
750	2084	723
1000	2779	963