Conceptos de la A - Z

Actúan como dispositivo de señalización o control de las operaciones en función de la posición del interruptor.  Pueden servir para bloquear el uso de otros interruptores y para la señalización de la posición del dispositivo.

Prensa cables PG (Panzer-Gewinde) han sido utilizados hasta 2004, fecha en la que fueron reemplazados por los equivalentes en métrica en aquellas envolventes fabricadas por Merz. Sin embargo, en algunos modelos que son adquiridos a terceros es posible seguir manteniendo el roscado PG. A continuación mostramos una tabla para comparar las dimensiones entre los diferentes tipos de prensa estopas.

Los conmutadores de levas según su configuración se componen de unas cámaras que alojan pueden alojar hasta tres contactos con dos puntos de interrupción cada uno. Cada circuito está compuesto por dos terminales fijos y un contacto móvil que se mueve por la acción del mando sobre una leva.

El puente de contactos es abierto positivamente a través de una leva y cerrado a través de un resorte.  Estos dispositivos se encuentran disponibles para diferentes torques y ángulos de conmutación. Los terminales son a prueba de contactos directos, y cuentan con tornillos imperdibles, guías para el destornillador y topes para asegurar la correcta inserción del cable.

Los conmutadores de transferencia Merz de la serie MN se utilizan para conectar una alimentación a dos cargas independientes o para conectar dos fuentes independientes con una carga. Un ejemplo típico de la segunda categoría es el interruptor "Red-0-Generador", que primero desconecta la fuente de alimentación principal  y luego cambia el suministro a un generador de respaldo. Los interruptores de transferencia están disponibles con hasta 8 polos con o sin posición 0.

Son conmutadores que tienen un esquema de conexión que  simula una codificación binaria. Estos conmutadores pueden generar como máximo un código binario de 0 a 11.

El término "interruptor compacto" es comúnmente utilizado a nivel de marketing en la industria eléctrica y se refiere a un diseño específico de interruptores o conmutadores de transferencia, que tienen una disposición idónea para ser integrados en un tablero de distribución. En la mayoría de los casos, los interruptores están adaptados bien sea para el montaje en el riel DIN o a fondo de armario, o montaje frontal en la puerta. Todos los tornillos de terminales son accesibles desde el lado contrario al montaje y alineados en la dirección del cableado. El término no está definido por ninguna normativa internacional. Las series ML0 a ML3 son la serie de interruptores compactos de MERZ.

Los diagramas que se presentan en este  catálogo muestran a todos los contactos principales como normalmente abiertos. Si alguno de ellos en cierta posición de conmutación se encuentra cerrado, se indica en la matriz con una X. Este tipo de diagrama permite, especialmente en los conmutadores de levas que tienen muchas posiciones, una ilustración mucho más simple y transparente de las funciones de conmutación.

Es la corriente que un dispositivo puede soportar sin que su temperatura sobrepase unos límites establecidos por la norma, estando dentro de una envolvente específica. IEC/EN 60947-1; 4.3.2.2

La corriente térmica convencional Ith es la corriente máxima que se utiliza en la prueba térmica de dispositivos eléctricos al aire libre. Esta debe corresponder con la corriente de funcionamiento máxima nominal de un dispositivo durante una operación continuada por ocho horas. El aire libre se entiende como aire en habitaciones interiores comunes casi libre de flujo de aire y radiación. IEC/EN 60947-1; 4.3.2.1

Factores de conversión para las corrientes de carga permitidas en líneas y cables aislados con PVC a temperaturas ambiente distintas a 25 °C

La Ley de Reforma y Protección del Consumidor de Dodd-Frank de Wall Street (comúnmente conocida como Dodd-Frank) es una ley federal de los Estados Unidos que se promulgó el 21 de julio de 2010. La ley revisó la regulación financiera después de la Gran Recesión, e hizo cambios que afectaron a todas las agencias reguladoras financieras federales y a casi todas las partes de la industria de servicios financieros de la nación.

Dodd-Frank reorganizó el sistema regulatorio financiero, eliminando la Oficina de Supervisión de Ahorros, asignando nuevas responsabilidades a agencias existentes como la Corporación Federal de Seguro de Depósitos y creando nuevas agencias como la Oficina de Protección Financiera del Consumidor (CFPB). A la CFPB le fue encomendada la labor de proteger a los consumidores contra abusos relacionados con tarjetas de crédito, hipotecas y otros productos financieros. La ley también creó el Consejo de Supervisión de la Estabilidad Financiera y la Oficina de Investigación Financiera para identificar amenazas a la estabilidad financiera de los Estados Unidos, y dio a la Reserva Federal nuevos poderes para regular instituciones sistémicamente importantes. Para manejar la liquidación de grandes empresas, la ley creó la Autoridad de Liquidación Ordenada. Una disposición, la Regla Volcker, restringe a los bancos a hacer ciertos tipos de inversiones especulativas. La ley también derogó la exención de la regulación para los swaps basados en valores, que requiere que los swaps de incumplimiento de crédito y otras transacciones se liquiden a través de intercambios o cámaras de intercambio.

CEM (EMC, en inglés)  se define como la capacidad de un dispositivo para funcionar satisfactoriamente en su entorno electromagnético sin que origine perturbación alguna que sea inaceptable en él u otros equipos cercanos.  

Los dispositivos que carecen de  circuitos electrónicos, como, por ejemplo, los interruptores de desconexión y conmutadores de levas, pueden emitir interferencias electromagnéticas durante operaciones de conmutación ocasional, que apenas duran unos milisegundos. Como resultado, se supone que cumplen con los requisitos de compatibilidad electromagnética y no es necesaria ninguna verificación adicional. Sin embargo, la situación es diferente si los interruptores forman parte de una instalación donde se utilizan como interruptor de reparación y mantenimiento aguas arriba de un motor controlado por un variador de frecuencia. Dicho controlador puede emitir interferencias que hacen necesario un blindaje electromagnético de la línea de suministro, incluyendo por supuesto el interruptor. MERZ ofrece una gama completa de envolventes apantalladas tanto en material plástico como metálico, que permiten cumplir con los requisitos de compatibilidad electromagnética . Los interruptores de leva MN y los interruptores compactos ML son completamente resistentes y no pueden ser influenciados por interferencias externas

En ciertas máquinas es necesario que el interruptor principal cumpla con la función de ser una unidad de parada de emergencia. Para diferenciarse de un interruptor estándar y por razones de seguridad el mando debe ser de color rojo mientras que la base debe ser amarilla. Las unidades de parada de emergencia operadas manualmente deben tener apertura positiva de los contactos, además de estar fácilmente accesibles.

Para adaptar los interruptores  MERZ a varias profundidades de tableros o equipos hay disponible una amplia gama de extensiones de eje, tanto para la serie de conmutadores de levas MN como para los  interruptores compactos ML. Con estas extensiones se pueden cubrir profundidades desde los 18 mm hasta los 405 mm. También existen soportes cuando el eje es largo para evitar posibles desviaciones.

Se refiere a la capacidad de un contacto para conmutar señales de control sin fallos. Los contactos de los conmutadores de levas y de los interruptores compactos están diseñados para corrientes y voltajes superiores. Se considera que los valores mínimos críticos son 1A y 24V. En caso de valores inferiores se recomiendan utilizar contactos chapados en oro.

El conmutador de grupo es una subcategoría de conmutadores de paso. Mientras que los interruptores de paso abren y cierran los contactos por separado para cada paso, los conmutadores de grupo permiten mantener los contactos cerrados para varios pasos del conmutador.

Relative to suitability for various ambient conditions electrical devices are classified in different degrees of protection, so-called IP-codes. The abbreviation IP according to DIN stands for „International Protection“, anyhow English speaking countries translate it as „Ingress Protection“. They are listed in the DIN EN 60529 with the header „Degrees of protection by means of enclosures (IP-code)“.

If one of the figures not needs to be mentioned it will be replaced by an „X“

Additional information is available in IEC/EN 60529

Function for complete power supply disconnection of a facility or part of it, whereas the facility must be completely separated from any source of energy for safety reasons. The position of the main contacts must be clearly and effectively displayed. The switch disconnector must be lockable in the OFF-position according to IEC/EN 60204-1. Increased requirements for actuators stability are based on IEC/EN 60947-3 in order to avoid, that the actuator can be moved to the OFF-position in case of welded contacts. IEC/EN 60947-3; 8.1.7

Line and cable entry points in housings and average values for the sealing zones of cable glands.

IEC/EN 60204-1 is applicable for the safety and electrical equipment of machinery. The application of these normatives serves as well to achieve the safety aims of the EC machinery directive. A manually operated main switch has to be provided for every mains supply. As switch-disconnector it must comply with utilisation category AC-23 and fulfil following requirements:

- disconnecting the electric device of the mains, showing a single ON and OFF position each only, clearly marked with 0 and 1. In addition a triggered position is admissible.

- visible isolating distance or position indicator showing the OFF position only in case all contacts are opened in fact and a sufficient clearance according to the normatives is achieved. In case the main switch is not used as an emergency-off switch at the same time, red is excluded as its handle colour. Than black or grey are recommended colours.

- It has to be lockable in OFF-Position (e.g. by padlocks)

- All active conductors have to be disconnected of the mains. In TN net systems it is admissible to separate or not to separate the N-conductor.

- The rated breaking capacity has to be sufficient to break the current of the biggest motor in blocked state together with the sum of all operational currents of all other motors/consumers. However, the admitted rated thermal current has not to be exceeded!

- The handle of the main switch must be easily accessible and must be situated in a height between 0,6 and 1,9 m of the floor level.

Colloquially called voltmeter and ammeter selector switches, offered for the most different types of mains networks. The range MERZ offers with switches of series MN covers all possible variations.

Multi speed switches are used for motors with 2 or more windings in order to vary the motor speed. There a several different versions available since the windings of such motors are either directly accessible via the motor terminal board or internally wired (Dahlander with tapped windings).

According to the German normative the neutral conductor might be switched, this without being a must. This differs e.g. of the situation in France. There the normative requires the disconnection of the neutral conduct of any equipment or machine equal to the other active conductors. This can be achieved by the MERZ cam switches (MN) due to their multitude of contact arrangements as well as by the MERZ compact switches (ML).

Corresponding to the series the contacts are else integrated in the basic versions or available as separate additional switch contacts for add on mounting. The switched neutral contact has to break after the other contacts and to make in advance of the other contacts! IEC/EN 60947-1; 8.1.9

KEMA KEUR, UL, CSA, CCA Protocol
All MERZ switchgear products are under steady inspection in our own test facilities. Beside that, all products have been tested by independent notified bodies and are subject to KEMA, UL and CSA approvals. Within Europe and the countries located at the Mediterranean Sea the notified bodies have agreed, that the testing must be performed according to the IEC/EN norms and is therefore mutually valid. Because of this regulation all MERZ switchgears are carrying the KEMA KEUR sign and are CCA certified which is documenting the international acceptance.

Switch breaking or making one or multiple mains contacts simultaneously. Additional auxiliary contacts (NO/ NC) making/breaking as well in contrary can be included. Auxiliary contacts of series ML can carry up to 10A. Auxiliary contacts of series MN usually carry the same current as the main contacts. Exception is made at very large cam switches only, where a small auxiliary is coupled. (switch coupling).

Outside diameter of lines and cables.

Operating conditions that are causing an overload current within an electrically correct circuit.

Permissible current load and protection against overload of lines and cables for permanent installation at ambient temperatures of 25°C.

finds application in the manufacture of unbreakable household items and technical parts where high abrasion resistance is required, such as dowels, screws, housings, bearings, insulation parts for electrical systems, cable ties, adhesive bases, etc.
Because of its resistance to lubricants and fuels at temperatures up to over 150 °C it is also used in vehicle manufacturing for parts that are built onto the engine such as suction systems, fuel pipes, engine covers etc.
The two most frequently used polyamides are PA 6 and PA 6.6. Their manufacturing process is fundamentally different. PA 6.6 and PA 6 are nevertheless chemically and physically very similar and differ only in their mirrored arrangement of one CH2-NH-CO group.

are synthetic polymers from the polyester family. Polycarbonates are crystal clear, can be coloured, welded and glued and are also very dimensionally stable and possess high impact resistance.
Because of its higher cost relative to other plastics, polycarbonate is almost only used where others are too soft, too brittle, too prone to scratches, insufficiently dimensionally stable or not sufficiently clear. PC also excels for its high UV resistance and good electrical characteristics. MERZ uses PC for the enclosure series I7 and higher.

other names: polystyrene,
IUPAC name: poly(1-phenylethane-1,2-diyl)) is a transparent, amorphous or partially crystalline thermoplastic. PS can be dyed in all colours. Amorphous polystyrol is a common plastic that finds application in many areas of everyday life.
Polystyrol is used either as a thermoplastically workable raw material or as an expanded material. In electrical engineering polystyrol is used for its good insulating qualities. As well as for the insulation of cables it is used in the manufacture of switches, bobbins and housings (high-impact polystyrene, HIPS) for electrical equipment. Admittedly PS is only limited UV-resistant. Therefore it is not usable for outdoor use. PS is used for the production of the series 89xx and I1-S up to I3-S.

According to IEC/EN 60947-5-1 positively driven contacts must guarantee, that the contacts are completely opened as a direct result of a defined movement of a switch actuator without springloaded parts, when the actuator has travelled the forced disconnection travel at a manufacturer specified force.

Pulse contacts are used for additional triggering mostly of contactors or relays. In particular motor controls utilise
pulse contacts for activating an additional net-relay.

Rated value of current, a switching device can satisfactorily break corresponding to its utilization category. The rated breaking capacity is stated by reference to the rated operational voltage and rated operational current according to the relevant device norm. A switching device must be capable of breaking any value of current up to and including its rated breaking capacity. IEC/EN 60947-1; 4.3.5.3

From the manufacturer declared unaffected current, that a switching device (e.g. switch-disconnector), protected by a manufacturer specified short-circuit protective device (e.g. motor protection switch), can carry during the disconnecting time of such device under in the individual device norm specified testing conditions. The manufacturer must specify the details of the short-circuit protective device. IEC/EN 60947-1; 4.3.6.4

Peak value of an impulse voltage at a specified form and polarity under which the switching device can be stressed at specified testing conditions without malfunction and whereas the sparking distance is referred to. The rated impulse withstand voltage of the switching device must meet or exceed the impulse overvoltage (transient overvoltage) that may occur in the circuit the device is operating in. IEC/EN 60947-1; 4.3.1.3

The rated insulation voltage of equipment is the value of voltage to which dielectric tests and creeping distances are referred to. The maximum rated operational voltage by no means can be higher than the rated insulation voltage. IEC/EN 60947-1; 4.3.1.2

Rated value of current, a switching device can satisfactorily make corresponding to its utilization category. The rated making capacity is stated by reference to the rated operational voltage and rated operational current according to the relevant device norm. IEC/EN 60947-1; 4.3.5.3

Rated current a switching device can carry in uninterrupted duty, taking into account rated operational voltage, rated frequency, rated operational mode, utilization category and ambient temperature. IEC/EN 60947-1; 4.3.2.3

Voltage of a switching device, which, together with the rated operational current, determins the application of the device and where all the different examinations and utilization categories are referred to. For single pole devices the rated operational voltage is in general the voltage over the pole. For multiple pole devices it is in general stated as chained voltage. IEC/EN 60947-1; 4.3.1.1

Short-circuit current a switching device can break at the rated operational voltage and frequency at a defined power factor for AC or a defined response time for DC applications. It is expressed by the maximum peak value of the unaffected current, that such device can break under specified conditions. IEC/EN 60947-1; 4.3.6.3

Short-circuit current a switching device can make at the rated operational voltage and frequency at a defined power factor for AC or a defined response time for DC applications. It is expressed by the maximum peak value of the unaffected current, that such device can make under specified conditions. IEC/EN 60947-1; 4.3.6.2

Short-time current that a switching device can carry under, in the individual device norm specified, test conditions without being damaged.
IEC/EN 60947-1; 4.3.6.1

For switching devices in switchboard installation Iu=Ith. For switching devices in an enclosure Iu=Ithe . Current a switching device can carry in uninterrupted duty (for weeks, months or even years). IEC/EN 60947-1; 4.3.2.4a

(Registration, Evaluation, Authorisation of Chemicals)
EU-Directive No.1907/2006,18. December 2006
REACH rules the use and handling of substances (chemicals) on their own, in preparations and in articles. REACH covers all (chemical) substances, doesn’t matter whether they are dangerous or not. On the side of the industry the following companies located in the EC must take actions according REACH:

• Producers (of chemicals)

• Importers (who bring chemicals into the EC)

• Downstream user (user of chemicals)

• Traders (of chemicals)

MERZ Schaltgeräte GMBH + CO KG is not producing chemicals or importing chemicals from non EU countries. Therefore we are not obliged to pre-register any substances at all. Based on the information we received from our suppliers, we expect that all substances we use are pre-registered in time.

Rated motor currents as quoted are for normal internally and surface cooled motors. Fuse: slow-blow or gL characteristic with specified lowest possible short-circuit fuse Direct start-up: max. start-up time 5 s, max. start-up current 6 x rated motor current Y start-up: max. start-up time 15 s, max. start-up current 2 x rated motor current.

Repair and maintenance switches are used to safely shut down machines and facilities that are not directly connected to a control unit or may bare the risk, that the machine or facility starts operating during maintenance or repair activities. The handle of such switches must be lockable by interlocks in order to prevent workers from hazardous situations and must meet the same requirements as main switches according to IEC/EN 60204-1

Reversing switches are used to change sense of rotation of AC motors. While switching from 1 over 0 to 2 two phases of the three phase alternating current net are interchanged in order to start the motor in the opposite direction. A typical application is the switching option W___/3. where all three phases of a motor are completely separated from the net in 0-position. In the next step the motor is switched on with two interchanged phases.
For motor-starter-combinations, where a net disconnector is used in front of the reversing switch, also 2 phases are interchanged. However, in this case the third phase is directly wired (switching option W___/2.). This switch is more compact but, as long as the net disconnector is not shut-off, continuously carries a load at the motor via the third phase.
Reversing switches are available with or without „0“-position. Also versions with both-sided automatic retraction in „0“-position are available.

EU standard 2002/95/EG (updated 21/10/2005)
The main contents are listings of banned substances no longer allowed to be a component in the products after the 01.07.2006. Limit values for that substances are set for Germany in the draft of the „ElektroG” dd. 01.09.2004. In 2003 MERZ GMBH already started to identify the relevant banned substances in the affected products. MERZ was determining and testing alternative substances.
Today MERZ products fulfil the requirements of the standard completely. We did not change the article numbers for the individual products.
Starting from 1. April 2006 we certify the conformity of our products affected by that standards according to the updated version of that regulation valid from 21.10.2005.

Safety switches are encapsulated main- repair or maintenance switches where the housing cannot be opened while the handle is locked by a padlock in OFF-position. MERZ safety switches are realized with the enclosure series I1 to I3.

Single-phase starter switches are used for starting of single-phase AC-motors. There are versions available for unidirectional or bidirectional motors with and without starter capacitors.

Star-Delta switches are needed to start larger three-phase alternating current motors with short circuit rotors rom 4kW upwards. The public power distribution network (230V/400V) does not allow start-up current higher than 60 Amps according to the TAB regulation. Motors with a capacity rating above 4 kW are therefore subject to a current limiting start-up mode. Such method prevents fuses to blow-up and potential voltage drops caused
by a very high start-up current in a direct switching mode. Star-Delta switches are offering the most compact and cost effective solution. There are versions with one or two rotating directions available. Furthermore the switches can be equipped with additional impulse mode contacts in order to activate or control additional contactors.

Step switches provide the widest offering in the MERZ MN product range. The switches are available from 3 to 12 positions with and without 0- position. All switches are available in 1-, 2- or 3-pole versions. Step switches are always activating one (respective 2 or 3 for 2- or 3-pole versions) contact only while switching from one position to the next whereas this contact will be disabled once the switch is moving to the successive position. There is no overlapping from one contact to the next during the changeover phase.

Switch disconnectors are mechanically operated switches in a circuit which are able to make, carry and break under normal operating conditions currents including a specified overload. In the open position the contacts fulfil the requirements of a disconnector. IEC/EN60947-3

In many applications it is necessary to control the machines and facilities by impulse or inching modes. In order to ensure that the device is not switching into constant modes MERZ has designed cam switches in such way, that the handle and the related switching contacts automatically move back into the starting position once the handle is released. Typical examples are lifts, where the switch must be held until the upward or downward
movement has reached its wanted position or with pumps, that are usually operating only in one direction but may have to temporarily change directions i.e. for cleaning mode.

The MERZ UVR-Switches with undervoltage release are available for a power range from 32A - 63A. The undervoltage release switch (UVR) is an electromechanical device which automatically shuts down when the supply voltage falls below a certain value. In such case the handle moves back to the OFFposition. The switch has been designed to open its contacts (release-free) even though the handle is eventually blocked. The undervoltage release is required in many countries especially for machines with rotating tools.

Utilisation categories describe the application of switching devices, referring to load limit values set by the normatives. Differentiation is made between utilisation categories for „AC“ and „DC“. MERZ switchgear are applicable for AC and 3-phase current and designed and tested to the strictest AC categories AC-3, AC-22 and AC-23. As a result they are suitable as well for other „AC“ categories. Code letter „A“ and „B“ placed after the utilisation category refers to the used testing cycle within the respective test. „A“ in general names the more demanding test cycle as the switch has to survive more switching cycles. IEC/EN 60947-1