Abstract: A cassette to be used in a conveyor device for products, for instance food stuff. The cassette (18) comprises a thin, broad-sided and broken through casing of substantially uniform thickness having an openable cover of broken through type. The casing and cover are interconnected along one side of the cover in several joints (47) and are interconnectable at several locking locations (48) along an opposite side of the cassette such that the casing and cassette in spite of the broken through structure, form a rigid and strong unit when the cover is closed.

Abstract: A continuous method for heating a product having at least one faster microwave heating portion and at least one slower microwave heating portion to a uniform predetermined temperature sufficient to sterilize the product without loss of odor, taste, texture, color or vitamin content quality by transporting the product through a plurality of microwave fields including a first higher energy field and one or more successively lower energy fields, in which the first microwave field is attenuated to an energy level sufficient to heat the fast microwave heating portions of the product to the predetermined temperature, the successively lower energy microwave fields are attenuated to an energy level sufficient to maintain the temperature of the faster heating portions and heat the slower heating portions to the predetermined temperature, and the transport of the product through the successively lower energy microwave fields is continued until the slower microwave heating portions of the product reach the predetermined

Abstract: A sluice device for insertion between zones having different environmental conditions, for instance pressure and/or temperature. A drum is rotatably arranged in an opening in a housing and has radially displaceable flaps uniformly distributed along the periphery of the drum. Each flap has a first portion for sealing against the housing, and a second portion of the flap, adjacent to the drum, cooperates with a sealing device. The sluice device is formed as a longitudinal groove which is open against the drum, whereby a longitudinal sealing member is arranged in the groove. The pressure difference between spaces at the two sides of the flap brings the longitudinal sealing member in such a sealing position that the flap, by the pressure difference, is placed in sealing abutment against the inside of the housing regardless of the positive or negative pressure difference.

Abstract: As overvoltage protection for a series capacitor (C1-C5) in a high-voltage network a voltage-dependent resistor (Z6), built up of metal oxide varistors, is arranged in parallel with the capacitor. In parallel with the resistor there is a spark gap means consisting of two series-connected spark gaps (G1, G2) for shunting the resistor in case of overload thereof. The energy for triggering the spark gap means is obtained from an auxiliary capacitor (C5), which is charged during operation, and is supplied to one of the spark gaps (G2) via a switching means (T1, T2), controlled by an overload detector (CU), and a pulse transformer (TR). A metal oxide varistor (Z5) is connected in series with the high voltage winding of the transformer. The transformer is connected so that the triggering pulse is in opposition to the voltage across the series capacitor.

Abstract: A surge arrester includes an elongated insulating housing comprising one or more stacks of electrically series-connected metal oxide varistor blocks arranged between a top terminal and a bottom terminal. To achieve a more even voltage distribution in the longitudinal direction of the surge arrester, the surge arrester comprises larger varistor blocks at the top terminal than at the bottom terminal.

Abstract: A surge arrester comprises two or more surge arrester units which are electrically series-connected between a top terminal and a bottom terminal. Each surge arrester unit comprises a stack of metal oxide varistor blocks, the latter being distributed within the surge arrester so that the number of varistor blocks per unit length in the surge arrester unit which is nearest the bottom terminal is less than in the surge arrester unit which is nearest the top terminal. This enables a more even temperature distribution to be achieved throughout the length of the surge arrester especially in the case where the surge arrester is located where it is subjected to long-term external fouling or pollution.

Abstract: In a surge arrester comprising a stack of series-connected cylindrical ZnO-varistors in an insulating housing, the envelope surface of each varistor is provided with an insulating protection means, which overlap varistors positioned adjacent to each other. The protection means prevent the varistors from being mechanically damaged during handling, provides guiding for the varistors in the stack, and seals the stack of varistors, so that a local glow discharge or a fault in individual varistors will not lead to an arc flash-over along the stack.

Abstract: Each unit of a heat-sensitive product is contacted directly or indirectly with a cooling medium so that the unit acquires a condition in which a surface layer thereof has a lower temperature than its inner portions. The product unit is then heated, by electromagnetic energy of at least microwave frequency, from this condition to substantially the desired sterilizing or pasteurizing temperature in a medium having a temperature which will permit such heating. In this way, a substantially uniform heat treatment effect is obtained in the product units.

Abstract: Separate units of a heat-sensitive product are each pre-treated by heating at least the main part of the unit to a pre-heating temperature of at least 50.degree. C., a cooling medium being brought into direct or indirect contact with the unit so that its surface layer is prevented from acquiring a substantially higher preheating temperature than its inner parts; and each product unit is then heated to substantially sterilizing or pasteurizing temperature by electro-magnetic energy of at least microwave frequency.