Abstract: For monitoring the appropriate operation of a plurality of control loops having the same setpoint, the control ratio is measured at each controller, is normalized and an alarm signal is generated if said normalized control ratio exceeds a predetermined alarm band.

Abstract: In an apparatus for contact-free transmission of condition responsive electrical signals from a rotating machine part to a stationary machine part a single rotational transformer having a stationary primary winding and a rotating secondary winding is used for (a) transmitting power supply signals from a stationary evaluation circuit to a rotating transducer, (b) transmitting condition responsive measuring signals from the transducer to the evaluation circuit, and (c) transmitting synchronizing signals between the transducer and the evaluation circuit.

Abstract: The properties synchronous motors are provided to an asynchronous motor fed with the aid of a digital speed control via a static converter. For this purpose, a signal proportional to an integral of the rotation-speed deviation, and a signal corresponding to the rotation-speed set-point value, are multiplied with each other and therefrom is obtained the control-pulse sequence for the converter. From an input sequence corresponding to the measured rotation speed, a signal corresponding to the period duration of the rotation-speed measurement-device frequency is obtained, and this signal is divided by a value corresponding to the rotation-speed set-point value. The period-duration signal referring to the rotation-speed set-point value thus obtained is switched opposite to the control-deviation signal, before the control-deviation signal is fed to the multiplier.

Abstract: A humidity sensor operates with a capacitive sensor element (C.sub.S) which is arranged in one branch of a free-running multivibrator (MV), whereas a reference capacitor (C.sub.ref) is arranged in the other branch of said multivibrator. Both output signals (U1, U2) of said multivibrator (MV) are averaged by means of RC elements (R3, C1; R4, C2) and supplied to a differential amplifier (DV), the output signal (Ua) of which changes the operating voltage (U.sub.B) of the multivibrator (MV), and therefore, linearizes the characteristic of the capacitive sensor element (C.sub.S).

Abstract: A device for dynamically measuring the degree of dirt accumulation on bank-notes in which certain areas of the bank-note are illuminated and examined by means of a receiving unit. The light from a succession of adjacent elemental areas of a bank-note so illuminated is dependent upon the degree of dirt accumulation and is converted into a corresponding electric signal. The signal is analyzed to determine the number and amount of changes due to dirt accumulated in creases, and the analyzed signal is integrated to determine whether or not the number and nature of areas of accumulated dirt makes the ban-note unsuitable for further circulation.

Abstract: The paper carries, at one or more points, materials which, in the excited condition, fluoresce in the visible, ultraviolet, or infra-red spectral range in the characteristic emission spectra. The device includes a light source for exciting fluorescent substances, a condenser lens concentrating the light emitted by the paper, a narrow band interference filter, a focusing lens, and a series of photocells arranged in the focal plane of the focusing lens. The geometric arrangement of the photocells is chosen appropriately to identify an emission-line doublet. The outputs of the photocells are fed to a pre-amplifier and then to a comparator which may effect a subtraction of the amplified photocell output to provide an output signal. In a variation, the quotient of the photocurrents of two photocells is compared to establish the authenticity of the paper.

Abstract: In the arrangement, a batch or stack of vertically oriented recording media sheets is supported on edge on a horizontal vibrating table which is vibrated by a vibrating conveyor and the sheets are advanced singly, starting with the leading or frontmost sheet, through a separating slot between a pair of endless belts constituting a transporting arrangement. A first rotating suction drum is mounted at the rear end of the vibrating table and is formed with circumferentially spaced suction bores for operative relation with a rotary slide valve to connect the suction bores intermittently to a suction system. A second rotating suction drum is arranged within the range of the separating slot and serves as a separating drum, and a hold-back suction drum is also arranged within the range of the separating slot and serves as a hold-back device, the hold-back suction drum having the same design as the first rotating suction drum.