| 摘要 |
An adjustable heater for aquaria, comprising a substantially tubular container (2) within which are housed an electrical heating element (3), a switch (6) comprising s fixed contacts (7, 8) and moving contacts (9, 10) and capable of electrically connecting the heating element (3) with an external source (R) of electrical power, a temperature sensor (12) with a bi-metal strip (13) capable of detecting the temperature of the liquid and interacting with the switch (6) to move it from a closed position to an open position when a predetermined temperature (T) is to reached. The moving contacts (9, 10) of the switch (6) are secured to a free end (13") of the bi-metal strip (13) while the other end (13") of the bi-metal strip (13) is electrically insulated. This yields the advantage that electrical current does not pass through the bi-metal strip (13) and therefore does not create a Joule effect within it which affects the sensitivity and proper behaviour of the temperature Is sensor (12). |
