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plugs and sockets |
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plugs and sockets |
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| Japan
has a 100V network. Standard, domestic plugs and sockets are nearly
identical to North American type A and B 120V-15A devices. Plugs and
sockets for higher currents and voltages differ from the North American
NEMA configurations. Some examples of heavy duty devices are shown
below. They are either single phase or split-phase.
The museum collection does not have any Japanese three-phase plugs or
sockets. One Chinese split-phase plug (no. 4) has been added to this section, because it resembles a Japanese plug. |
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| 1 | Japanese
200V, 15-20A single phase socket. The right hand, U-shaped slot is the
earth connection. In addition there is also a connector - hidden behind the flap below
the outlet - for a ground adapter (see type
A/B domestic plugs, item 6). 200V originates from a 208V nominal
voltage system, which means 208V at the point of supply and an
utilization voltage of 200V 'at home'. Usually there is a 3-5% voltage
drop in transport lines from transformer station to residence. 200V-15A plugs have two straight blades in line (+ earth pin), while 20A plugs have a straight and L-shaped blade. |
| 2, 3 | Japanese 250V, 15A, split-phase socket and plug. To wire up the plug you simply have to lift up the brown, circular base plate. 250V nominal corresponds to an utilization voltage of approximately 240. Split-phase electrical power is explained below. |
| 4 | Chinese 380V, 15A, split-phase plug.
Confusion with the
Japanese lookalike (no. 3) is excluded because of the difference
in width and spacing of the pins. China has a 220V - and
thus 380V three-phase - network for domestic purposes. |
| 5, 6 | Japanese locking type 250V, 20A single phase socket and plug. To wire up the plug you have to lift up the white base plate. |
| 7, 8 | Japanese locking type 250V, 20A split-phase socket and plug. |
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Split-phase systems are often found in
houses that are connected to a 125V network, because only three wires
(plus an equipment or protective ground) are needed for both single
phase 125V and 250V. To achieve this the output coil of the transformer
is center-tapped (red dot in the scheme at left) and connected to
neutral. A combination of the top or bottom live pole and the neutral pole at left (see scheme) provides for 125V which is used for lighting and small appliances. 250V is obtained by connecting the top and bottom live poles. This higher voltage is used for stoves, heaters, dryers and air conditioners. Powering such equipment with 120V would require a higher current, thicker wires and larger plugs and sockets. Note that 250V and 125V are nominal voltages. 2.4 kV at the input side of the transformer is taken as an example. Input voltages may differ locally. |
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