a traditional rcd wont work as it uses the difference between the incoming active and neutral to detect current loss it has to read 0.
In particular, an RCD alone will not detect overload conditions, phase to neutral short circuits or phase to short circuits. Over-current protection must be provided.
No, it is not possible to connect a 3-phase 440 V system without a neutral line to a machine that requires a 3-phase 4-wire connection with a neutral line. The neutral line must be present in both systems for proper operation and safety. Trying to connect them without the neutral line could cause damage to the machine and pose a safety hazard.
A smaller neutral wire in a three phase system can be used because it does not carry the full line current. It carries the unbalanced current of all three leg loads. This is one reason that three phase loads on a distribution panel should be equalized as much as possible to reduce the current on the neutral.
In three-phase there are three live wires and a neutral. The voltage of a three-phase system is always quoted as the live-to-live voltage, and the voltage from one live wire to neutral is 57.7% of that. A 440 v 3-ph system has 254 volts between live and neutral. <<>> The question statement is not correct. Two legs from a three phase three wire 440 volt system will still be 440 but classed a single phase. On a three phase four wire system supply, the voltages will be determined by the following equation. 440/(square root of 3) 1.73 = 254 volts. The second single phase voltage attainable from this source connection is any one of the three phase legs to grounded neutral center point. This is known as a wye or star point connected voltage supply. To obtain a 220 volt single phase voltage, the three phase system would have to have a voltage of 220 x 1.73 = 380 volts.
There are usually 3 or 4 terminals. If only 3, then each wire is hot with respect to ground. If there are 4, then one wire is considered neutral.
In three phase: I = (three phase VA) / (sqrt(3) x (phase to phase voltage)) for single phase: I = (single phase VA) / ((phase to neutral voltage)) keep in mine three phase VA = 3 x (single phase VA), and phase to phase voltage = 1.732 x (phase to neutral voltage) Therefore the single phase and three phase currents are the same (ie, the three phase currents are the same in all three phases, or balanced). But don't get available current and available power confused (KVA is not the same as KW).
A three phase system will have 3 phase branch circuits and no neutral.
Only one neutral conductor is typically in a 3 phase panel.
If the heater is rated as a 3 phase 480 volt heater then a neutral is not needed. If the voltage stated is 277 volts three phase then a neutral is needed.
415V 3 phase is the line to line voltage. The line to neutral of this supply is 230V single phase. Therefore you use one of the phases and the neutral.
Usually yes. A typical 480 volt panel is a 3 phase panel with 480 volts line-to-line and 277 volts line-to-neutral. However, I did once see a panel that was 480 volts, 3 phase, but because it served only motors it did not have a neutral. (a 3 phase motor doesn't use a neutral.) Similarly, if a panel uses only 2 legs of a 3 phase 480 volt system, which would be called single phase, it would not require a neutral if it only feeds 480 volt single phase loads. But I find the idea of no neutral to be extremely unusual and in my one personal experience, I blamed it on the age of the system. In 16 years of commercial and industrial construction I have never installed a 3 phase panel without a neutral and all my work is designed by engineers.
The formula to use is, phase voltage /1.73 = phase to neutral (ground) voltage.CommentThere is no such thing as a 'phase to phase', or 'phase to neutral' voltage. The correct terms are 'line to line' and 'line to neutral'. So the above answer should read: line voltage/1.73= line to neutral voltage = phase voltage.
A three phase delta system does not use a neutral in its operation.
No, it is not possible to connect a 3-phase 440 V system without a neutral line to a machine that requires a 3-phase 4-wire connection with a neutral line. The neutral line must be present in both systems for proper operation and safety. Trying to connect them without the neutral line could cause damage to the machine and pose a safety hazard.
As far as I understand, you don't need neutral line for connecting appliances that is 3-phase compilant. You only need the neutral line to connect a single phase appliance, which you connect along with one of the three lines.
You can divide a three phase service into (3) single phase circuits providing you have a 4th neutral wire.
Floating neutral in 3 phase supply is undesirable as if the same thing occurs then there will be bad effect for all single phase equipment which we are using as phase to neutral voltage will exceed from its normal value and it will harm the equipments.
The current is the same in the three live wires. The voltage can be described as the line voltage (phase to neutral) or the phase voltage (phase to phase) which is larger by a factor of sqrt(3). So a line voltage of 230 v corresponds to a phase voltage of 400 v.