What is the voltage on the wild leg of Delta?
It's like 120 / 240V but also provides 240V 3 Phase for large loads (Machinery, etc.). It's often called “Wild Leg” of “High Leg” Delta because one leg (Phase B) is different. Accordingly, what is the voltage on each leg of 3 phase?
What is a high leg 3 phase?
This type of service, which is also known as a “high-leg”, “wild-leg”, “stinger leg”, or “wild phase” service, is common in older manufacturing facilities with mostly three-phase motor loads and some 120 volt single-phase lighting and plug loads. Also, can you get 240v from 3 phase?
What does 3p4w mean in power?
240V 3 Phase Open Delta (3P4W) In the US, 240V Power is provided to small buildings with large loads as 240V 3 Phase Open Delta. It’s like 120 / 240V but also provides 240V 3 Phase for large loads (Machinery, etc.). It’s often called “Wild Leg” of “High Leg” Delta because one leg (Phase B) is different.
What is a wild leg on a transformer?
The "wild leg", also known as the "high leg" exists in any 120/240 three-phase service, where there is 120 volts from phase A to neutral, and from phase C to neutral, but there is 208 volts from phase B to the neutral. It is a necessary characteristic of a phase A to phase C transformer which has a grounded center tap,...
What is the voltage on each leg of 240 3 phase?
What is the voltage on each leg of 3 phase?
What is a phase leg?
What voltage is the high leg on 3 phase power?
What is wild-leg voltage?
Is there such thing as 240V 3 phase?
What is a wild-leg in electrical?
How does 208V 3 phase work?
Is 208 3 phase delta or wye?
| Description | L–N Vac | WattNode Models (Wye or Delta–Voltage) |
|---|---|---|
| 3-Phase, 3-Wire 208 V Delta (No neutral) | – | 3D-240 |
| 3-Phase, 3-Wire 230 V Delta (No neutral) | – | 3D-240 |
| 3-Phase, 3-Wire 400 V Delta (No neutral) | – | 3D-400 |
| 3-Phase, 3-Wire 480 V Delta (No neutral) | – | 3D-480 |
What is the voltage on each leg of 480 3 phase?
What is a wild leg transformer?
The wild or high leg of a service transformer is only associated with the Delta transformer. (For the remainder of this article, the term “power leg” will be used in place of high leg or wild leg.)
Why does the power leg only have odd voltage when it is referenced to ground?
Again, this is because it is working through an entire winding and another half winding with an angle in between. This does not hold true for phase B and phase A referenced to ground. They simply split the one winding between phase A and B in half.
What happens when a Delta transformer is center tapped?
This center tap is grounded to a ground rod driven into the earth, which grounds the neutral wire and the equipment’s chassis.
How many 120V windings are there in a transformer?
Notice that when the winding of the transformer was center tapped to ground, it divided the total winding voltage (240 V) into two 120-V windings connected in series (Figure 1). This happened because the winding was divided perfectly in half. Both phase A and phase B relative to the center tap or ground would be 120 V, and could be used for any single-phase, 120-V sources.
Can you connect phase C to 120 volt load?
Figure 2. Never connect Phase C to a 120-volt load. The load will see 208-210 volts in this case and fail from too high a voltage.
Can you wire a power leg to a 120V source?
The power leg is an unusually colored orange, so it can be readily recognized. Never wire the power leg to a 120-V source! It should only be used on 240-V, three-phase loads or 240-V, single-phase loads. If it is hooked to a 120-V, single-phase load, the load will eventually fail from too high of a voltage source.
What is phase B?
One of the phase-to-neutral voltage (usually phase "B") is higher than the other two. The hazard of this is that if single phase loads are connected to the high leg (with the connecting person unaware that that leg is higher voltage), excess voltage is supplied to that load. This can easily cause failure of the load.
Why is the high leg of a transformer called orange leg?
It is called "orange leg" because the wire is color-coded orange. By convention, the high leg is usually set in the center (B phase) lug in the involved panel, regardless of the L1-L2-L3 designation at the transformer.
How to supply high leg delta?
High-leg delta service is supplied in one of two ways. One is by a 3-phase transformer (or three single-phase transformers), having four wires coming out of the secondary, the three phases , plus a neutral connected as a center-tap on one of the windings. Another method (the open delta configuration) requires two transformers. One transformer is connected to one phase of the overhead primary distribution circuit to provide the 'lighting' side of the circuit (this will be the larger of the two transformers), and a second transformer is connected to another phase on the circuit and its secondary is connected to one side of the 'lighting' transformer secondary, and the other side of this transformer is brought out as the 'high leg'. The voltages between the three phases are the same in magnitude, however the voltage magnitudes between a particular phase and the neutral vary. The phase-to-neutral voltage of two of the phases will be half of the phase-to-phase voltage. The remaining phase-to-neutral voltage will be √ 3 /2 the phase-to-phase voltage. So if A-B, B-C and C-A are all 240 volts, then A-N and C-N will both be 120 volts, but B-N will be 208 volts.
What is a high leg delta?
High-leg delta (also known as wild-leg, stinger leg, bastard leg, high-leg, orange-leg, red-leg, dog-leg delta) is a type of electrical service connection for three-phase electric power installations. It is used when both single and three-phase power is desired to be supplied from a three phase transformer (or transformer bank).
Is a high leg a split system?
If the "high leg" is not used, the system acts like a split single-phase system, which is a common supply configuration in the United States. Both three-phase and single split-phase power can be supplied from a single transformer bank. Where the three-phase load is small relative to the total load, two individual transformers may be used instead ...
How does a three phase system work?
The three phase system including single phase power from the secondary of the distribution transformer through insulated wires enters the meter box and safety switch and finally enters in the main panel box. Each line or hot wire connects to a separate bus-bar in the panel box for further distribution. Keep in mind that the color of High leg delta wire is orange denoted by “C”. In older cases, the middle wire as high leg delta in the orange color was denoted by “B” phase “NEC-2008”. Three poles, two poles and single pole circuit breakers are used to snap (i.e. in the metal tracks to hold the CB’s tightly) over three busbars including Wild leg delta which draws HOT from each busbar.
What is 208V single phase?
208V single phase can be achieved between high leg delta (orange color) and neutral. In this case, we have connected a hand dryer (208V, 15A) to a single pole breaker. The single pole breaker is connected to High-Leg Delta as hot wire, neutral and ground wire.
How to Wire High Leg Delta, 208V, 1-Phase Circuits & Breakers?
The following tutorial shows how to wire a 208V single phase breaker fed up by a high leg delta busbar for residential and commercial uses.
How to Wire 240V, 1-Phase Circuits & Breakers?
To do so, simply connect the appliance (water heater in our case) via two poles breaker connected to two hot wires (such as Hot 1 , Hot2 and Hot 3) and ground wire. Connect the additional neutral wire if needed.
How many transformers are needed for high leg delta?
For high Leg delta supply, the electric power supply company installs three transformers to provide 120V, 208V and 240V (1 & 3 Phase) supply voltage levels based on the end user requirement. The primary side of these three step-down transformers are connected to the 4.5k-7.2kV supply. The transformers then reduce the level of voltage to the desired 240V, 208V and 120V applicable to the commercial buildings and industrial installations.
How many wires are needed for a high leg delta panel?
In a high leg delta panel, we need four or five wires (three as hot) for three phase 240V circuits. As shown in the following fig, we have two appliances viz three phase motor and L21-30R or L21-20R outlet. You can see that we have connected all the three hot wires including the high leg delta. Additionally, we have connected neutral and gerund wires as well. You may do the same with other devices having the same design for connection such as surge protectors found in main disconnect switches, main distribution panel, sub panels, load centers and equipment locations.
What is a 3 pole outlet?
In 3-Poles, 240-250V, 3-Wires, Non-grounding, 3-Phase outlets such as 11-15R, 11-20R, 11-30R, 11-50R, L11-15R, L11-20R, L11-30R etc. You have only connect all three Hot wires i.e. there is no need to connect the ground and neutral wires.
What is the high leg of 240?
It appears you have 240 3 phase power, B phase is the high leg.
What is more important, voltage phase or amps?
More important is the voltage phase to phase when off and when running, and amps when running.
Do you need 115 for 3 phase?
There is no schematic indicating you have to have 115 to each leg of a 3 phase unit. A 3 phase unit only cares about the voltage across the legs, not to ground. A 3 phase 240v delta might have a higher voltage to one leg to ground, but this will not have anything to do with your rtu. Have your contractor find out why your unit tripping the breaker. What is your amerage when the breaker trips?
How many windings are there in a 120V winding?
You simply have 3 separate 120V windings, so from the center to any one of the three is 120V. Now, because of the phase offset, you can't just add any two and get 240. Because of the angular offset of the 3 phases, the algebraic sum becomes 208
Can a grounded center tap be used in a transformer?
with a grounded center-tap in one transformer secondary, the two grounds would be at different potentials and a problem would ensue --- but I have apparently been doing wiring in such a system, and have seen no problem.
What is the maximum power of a single phase circuit?
MAXIMUM POWER – In a single phase power circuit maximum power is calculated as the voltage times the current. If we assume it’s a 200A power circuit then the maximum deliverable power is 200 x 240 as follows.
What is 240V power?
240V power is used in the US and parts of the world. In the US 120 / 240V 1 Phase 3 Wire is the standard for homes and 240V 3 Phase Open Delta is the standard for small buildings with large loads. In parts of the world 240V Single Phase 2 Wire is the standard for homes.
What is the maximum power in Delta?
If we assume it’s a 200A power circuit then the maximum deliverable power is 200 x 240 calculated as follows.
Is 240V 3 phase or 120 / 240?
It’s like 120 / 240V but also provides 240V 3 Phase for large loads (Machinery, etc.). It’s often called “Wild Leg” of “High Leg” Delta because one leg (Phase B) is different. THE GOOD – It’s inexpensive for the power company and it provides 120V / 240V Single Phase and 240V 3 Phase.
Overview
High-leg delta (also known as wild-leg, stinger leg, bastard leg, high-leg, orange-leg, red-leg, dog-leg delta) is a type of electrical service connection for three-phase electric power installations. It is used when both single and three-phase power is desired to be supplied from a three phase transformer (or transformer bank). The three-phase power is connected in the delta configuration, and the …
Supply
High-leg delta service is supplied in one of two ways. One is by a 3-phase transformer (or three single-phase transformers), having four wires coming out of the secondary, the three phases, plus a neutral connected as a center-tap on one of the windings. Another method (the open delta configuration) requires two transformers. One transformer is connected to one phase of the overhea…
Explanation
Consider the low-voltage side of a 120/240 V high leg delta connected transformer, where the 'b' phase is the 'high' leg. The line-to-line voltage magnitudes are all the same:
Because the winding between the 'a' and 'c' phases is center-tapped, the line-to-neutral voltages for these phases are as follows:
Advantages
If the "high leg" is not used, the system acts like a split single-phase system, which is a common supply configuration in the United States.
Both three-phase and single split-phase power can be supplied from a single transformer bank.
Where the three-phase load is small relative to the total load, two individual transformers may be used instead of the three for a "full delta" or a three-phase transformer, thus providing a variety o…
Disadvantages
In cases where the single-phase load is much greater than the three-phase load, load balancing will be poor. Generally, these cases are identified by three transformers supplying the service, two of which are sized significantly smaller than the third, and the third larger transformer will be center tap grounded.
One of the phase-to-neutral voltage (usually phase "B") is higher than the other two. The hazard o…
Applications
It is often found in older and rural installations. This type of service is usually supplied using 240 V line-to-line and 120 V line-to-neutral. In some ways, the high leg delta service provides the best of both worlds: a line-to-line voltage that is higher than the usual 208 V that most three-phase services have, and a line-to-neutral voltage (on two of the phases) sufficient for connecting appliances and lighting. Thus, large pieces of equipment will draw less current than with 208 V, r…
See also
• Transformer
• Three-phase electric power
• Electric power distribution
• Mains electricity
• Mains electricity by country