Abstract: A reserve power system includes a reserve power machine (2) for the generation of power. The reserve power machine (2) is connected via a distribution network (4) to consumers (10,12) and elevator drives (8). The elevator drives include an elevator hoisting motor (28) and a frequency converter (26) controlling it. The elevator drives are provided with regulating devices (26, 44, 46) by means of which the speed of the elevator motor (28) is so adjusted that the power taken by the elevator drive (8) from the distribution network (4) is lower than an adjustable power limit (P.sub.A).

Abstract: A velocity-controlled elevator drive including an a.c. motor (28) driving elevator machinery regulated by means of a frequency converter (26) supplying the motor (28) with a controlled frequency and voltage. The load condition of the elevator is measured by means of a load weighing device (32) in the elevator car. A power limit (P.sub.A) is input to the elevator machinery as a reference value and the speed reference (38) given to the frequency converter is determined on the basis of the power limit (P.sub.A) and the load condition.

Abstract: A procedure for determining the position of an elevator car in which the code data contained in code units mounted in the building is read by means of a code data detector unit (4) in such manner that a code unit containing floor data and door zone data is mounted essentially close to the threshold of the landing door on each floor and that the detector unit reading the floor data and door data is mounted essentially close to the threshold of the car.

Abstract: The invention relates to an apparatus for regulating the speed of an a.c. elevator motor (10) by means of a frequency converter (8) consisting of a rectifier bridge (12) and an inverter bridge (14) with an intermediate circuit between them. The frequency of the frequency converter is adjusted until it corresponds to a frequency reference (f.sub.ref) corresponding to the speed reference (v.sub.ref,v.sub.ref ') of the motor. The velocity of the motor (v.sub.real) is measured to form a speed feedback signal. According to the invention, the apparatus has elements (24,26) for correcting the speed reference (v.sub.ref) on the basis of the change occurring in the voltage (U.sub.c) of the intermediate circuit.

Abstract: The invention relates to a method for protecting an I/O electronic circuit against overvoltages. The I/O circuit of the electronic circuit is provided with a current path (1) comprising a first diode (V1N), through which current path a current (ip) flows when the mains voltage is negative, and with a second current path (2) comprising a second diode (V1P) and a thyristor (T1), the thyristor (T1) being fired by a time-delay circuit charged by a positive voltage, and that the current flowing through the current paths (1,2) is used to trigger a protection device.

Abstract: A method and device are disclosed for braking a squirrel-cage motor in which the motor is controlled in a manner known per se by means of a voltage converter and a control circuit which switches off the main current to the motor in a braking situation, whereupon a direct current is supplied to the motor windings. To achieve a simple and inexpensive braking control system, the direct current fed into the motor windings is obtained from a rectifier bridge formed in the braking situation via electrical control from certain semiconductor components of the voltage converter.

Abstract: A procedure for adjusting the stopping of an elevator as accurately as possible on desired level with the aid of the deceleration instruction (DR). From the elevator's deceleration instruction (DR) a sample is taken at the beginning and at the end of deceleration, these are compared with each other and the linearity of deceleration is adjusted on the basis of the result obtained. The invention also concerns an elevator deceleration measuring circuit for carrying out the procedure. The measuring circuit, connected to the deceleration instruction (DR) of the elevator, comprises a display unit such as for instance two light-emitting diodes (D4,D5) by which the result can be ascertained if the deceleration instruction is increasing or decreasing.

Abstract: An elevator speed control system permitting rotation of the motor with short-circuited rotor at full speed, wherein the thyristors controlling said motor permit the motor to rotate at full speed and when the elevator is running in the lighter direction, operation of the motor as generator at an over-synchronous speed. The system comprises a control unit assembled of components known in themselves in the art by which the instruction value is increased considerably past the actual value, whereby the motor with short-circuited rotor is left to rotate at full speed, and that on commencing retardation the instruction value is dropped directly to be consistent with the actual value.

Abstract: A control circuit for use with an electronic guard strip for preventing collision of the strip with a moving object. A control such as a relay, is connected to at least one antenna, which antenna forms a capacitor together with a base in its ambiance. A voltage generator conducts an alternating voltage to the antenna. The control and the antenna are connected in circuit relation to an amplifier. A change of voltage arising from any capacitive protuberation in the antenna is conducted to the control. The voltage from the amplifier is conducted through a rectifier to another amplifier that is connected so as to have its direct current gain as +1, but which amplifies any change of voltage occurring in the d.c. voltage input to a multiple and which further acts upon the control through a comparator.