In the preceding report, were described the characteristics of thermal switches at surrounding temperature 10°C.
In this report, however, are described some characteristics at various surrounding temperatures.
In our experiments, it was resulted that opening time (t_o) and critical current (i_o) increase and reclosing time (t_c) decreases as the surrounding tempaerature rises, in case of the thermal switch of hot-wire type.
On the contrary, the characteristics for bimetal type are opposite, compared with those for hot-wire type.
Two kinds of the action time, which are opening time (t_o) and reclosing time (t_c) of the hot-wire type can be indicated as following equations, t_o=Alog θ_m/θ_m-θ_o, t_c=Blogθ_m/θ_o
where θ_m=final temperature rise, θ_c=critical temperature rise=a/b-cT
T=surrounding temperature A, B, a, b, c=canstants.
Those relations for bimetal type are now under investigation.

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There are two kinds of circuits for the hot cathode fluorescent lamps of 600 V d. c. They were designed as the application of the fundamental operating circuit for 100 V d. c., which we have already shown.⁽¹⁾
These two circuits are given as follows.
(1) Several fluorescent lamps are connected in series, each lamp and circuit being indentical with that of the fundamental lamp and its circuit.
(2) Several fluorescent lamps are connected in series, too, but only one of them is the same lamp and circuit as that of the fundamental one, and for the rest commertial lamps are used. In this case the electromagnetic relay in the fundamental circuit has a pair of coils of magnet and as the same number of contacts as that of lamps. For the length of these lamps we can adopt the length of the usual 20 W and 40 W lamps. It is necessary to use proper number of lamps corresponding to the fluctuation of source voltages. Starting time is usually 0.5-1.5 sec. By comparing with the above two circuits we know that the minimum starting voltages at circuit (2) are less than at (1) when the same number of lamps are used. For example, when four 20W lamps are used, the auxiliary resistance values being 70Ω, the minimum starting voltages are 450V at circuit (2) and 375V at circuit (1) respectively.
In general the minimum starting voltages vary with the auxiliary resistance values; the higher the latter the lower the former. When the auxiliary resistance values are up to 100Ω, however, the lamps start like the instantaneous type rather than the preheating type.
We can decrease the minium starting voltages by using the ballast tube in stead of the metallic resistance. In this case the minium starting voltages are less than 300 V when four 20 W lamps are used.

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