Info

Guidelines

What size wire do I need for a 75 kVA transformer?

What size wire do I need for a 75 kVA transformer?

For example, a 75-kVA, three-phase, delta-delta connected transformer will be installed in an industrial facility. The primary or input voltage will be 480V, and the primary conductors will be 1 AWG THHN conductors.

What size feed 75 kVA transformer?

This transformer will be sized for continuous loads; therefore, the conductors must have an ampacity of at least 113A (90 × 125% = 112.5 = 113). In accordance with Table 310.15(B)(16), 2 AWG copper conductors have an allowable ampacity of 115A.

What is the largest size grounding electrode required?

A grounding electrode conductor (GEC) from an electrical service to a ground rod, pipe or plate type electrode is never required to be larger than 6 AWG copper or 4 AWG aluminum unless the GEC continues on from the rod, pipe or plate to connect another electrode that may require a larger GEC such as a concrete encased …

What is the weight of a 75 kVA transformer?

410.00 lb
Specifications

height 37 in (939.80 mm)
width 30 in (762.00 mm)
depth 20 in (508.00 mm)
Net Weight 410.00 lb(US) (185.973 kg)

How many amps is 75 kVA?

Three Phase Transformer

KVA 208V 480V
45 125 54.2
50 139 60.2
60 167 72.3
75 208 90.3

How much does a 75 kVA transformer weight?

Specifications

height 37 in (939.80 mm)
width 30 in (762.00 mm)
depth 20 in (508.00 mm)
net weight 410.00 lb(US) (185.973 kg)

How many amps can a 75 kVA transformer handle?

Three Phase Transformer

KVA 208V 480V
60 167 72.3
75 208 90.3
100 278 120
112 313 135

How do you size a grounding rod?

Ground Rod Length Ground rods come in both 8-foot and 10-foot lengths, with 8-foot being the most common size used in residential installations. As a rule, ground rods must be a minimum of eight feet long and should not be cut down.

What happens if a transformer is not grounded?

There is no return circuit to earth and therefore nothing can flow through you to earth and back to the transformer to cause a shock. One may therefore safely touch EITHER output lead and not receive a shock as there is no earth reference. However touching BOTH output leads simultaneously will give one a shock.

What kind of conductor do I need for a 112.5 kVA transformer?

For a 112.5 kVA transformer, 135A×1.25=169A, so use a 2/0 AWG conductor rated 175A at 75°C, per Table 310.16. Size the equipment grounding (bonding) conductor for the transformer primary based on the size of primary protection device, per 250.122 (A):

How big is a grounding electrode for a transformer?

You must size a grounding electrode conductor for a single separately derived system in accordance with 250.66, based on the total area of the largest secondary ungrounded (hot) conductor. This conductor shall connect the grounded conductor of the derived system to the grounding electrode as specified in 250.30 (A) (4).

Where does the grounded conductor connect to the grounding electrode?

This conductor shall connect the grounded conductor of the derived system to the grounding electrode as specified in 250.30 (A) (4). The grounding electrode conductor must terminate at the same point on the separately derived system where the neutral-to-case bonding jumper is installed [250.30 (A) (1)].

How big a bonding jumper do I need for a 45kva transformer?

You must size the bonding jumper in accordance with Table 250.66, based on the total area of the largest ungrounded (hot) conductor as follows: For a 45kVA transformer: 3/0 AWG secondary conductor=4 AWG copper bonding jumper. For a 112.5kVA transformer: 700 kcmil secondary conductor=2/0 AWG copper bonding jumper.

What are the requirements for grounding and bonding?

Article 250 contains the following grounding and bonding requirements: (1)t systems and equipment are required to be grounded. Wha (3)tion of grounding connections. Loca (4)ypes of electrodes and sizes of grounding and bonding T conductors.

For a 112.5 kVA transformer, 135A×1.25=169A, so use a 2/0 AWG conductor rated 175A at 75°C, per Table 310.16. Size the equipment grounding (bonding) conductor for the transformer primary based on the size of primary protection device, per 250.122 (A):

Do you need a grounding conductor for a transformer?

Photo 3. This separately derived system/transformer has a compliant system bonding jumper; however, the required grounding electrode conductor is absent. The grounding electrode makes the earth connection for the transformer secondary circuit. It must be an effective connection, and all grounding paths must be connected to it.

Why is grounding important to the electrical system?

System grounding helps reduce fires in buildings as well as voltage stress on electrical insu- lation, thereby ensuring longer insulation life for motors, transformers, and other system components.