Electric monitoring device for gap alterations - indicates clearance alteration between turbine moving blades and casing

摘要

Monitoring device indicates gap alterations between moving blading and casing in steam or gas turbines, in which a low alternating voltage, e.g. 0.5 volts, is available for indicating contacts between running blades, and casing, the voltage being applied over the earth brushes of the running gear. This voltage is provided from a direct current battery. As soon as, for example, contact occurs between guide blade and running blade, a very short circuit current flow over the earth brush which has the effect of lowering the alternating voltage. Thus the required voltage is no longer received by a contact relay via an amplifier and this sets off an alarm current circuit which either causes the occurrence to be indicated or the turbine to be adjusted.