Common Features of Electromechanical Switches Switching systems F Switching elements lie at the heart of all electromechanical switching devices and must correspond to the respective application. Essentially there are two basic types of switching system that differ in terms of their mechanical design and consequently their scope of application: F Lag between NC and NO contact function Lag (hysteresis) S S 2) 1) l Slow-action contacts l Snap-action contacts Slow-action contacts 2) Snap-action contact Switching diagram l On actuation, the normally-closed contact function is immediately followed by the normally-open contact function The switching diagram describes the function of the switching device in detail. l The changeover accuracy is not dependent on the approach speed l Consistently effective suppression of DC arc l Reliable contact-making also for extremely slow approach speeds S l The snap mechanism triggers the full opening width of the contact on reaching the changeover point l Due to the force reversal in the mechanical system, a different switching point occurs in forward and reverse travel. The lag is referred to as hysteresis. Fig. 1 shows the contact force during the switching cycle of a slow-action contact. Overlap l The switching principle of slap-action contacts makes overlapping of the NC/ NO contact function possible. The term overlap refers to the area, in which both the normally-closed contact as well as the normally-open contact are closed in connection with a changeover switch with delay. 12 l Mechanical input variables (force, travel, torque, angle) l Electrical contact-making in forward and reverse travel l Terminal designation l Point at which positive opening is achieved l Type of contact system 0 2N 1 0 21-22 Lag between NC and NO contact function It combines the mechanical input variables that act on the contact system via the actuator with the electrical output variables. The user can deduct the following information from the switching diagram: 21-22 l In this configuration there is no overlap of the NC/NO contacts. The switch provides a distinct OR-function. F Changeover point in forward travel Changeover point in reverse travel 13-14 l The switching points are identical in forward and reverse travel 1) 13-14 l Large distance/actuating travel between normally-closed and normally-open contact function Fig. 3 shows the contact force during the switching cycle of a snap-action contact. 23-24 l The approach speed controls the contact opening (closing) time Fig. 2 shows the contact force during the switching cycle of a slow-action contact with overlap. 11-12 l On actuation, the normally-closed and normally-open contact functions correspond to the movement of the impact pin 6.5Ncm 10 1.8 35 3 55 6 12,5N Slow-action contact Contact closed Contact open 75 6Ncm Snap-action contact Contact designation Enclosures Safety switches In accordance with DIN 50013 and DIN 50005 the terminal designations of the contact elements are always make up of two digits. Limit switches are supplied either in a moulded enclosure or a metal enclosure. Which material is to be selected for a specific application depends on the ambient conditions, the location as well as several other factors. The scope of application for limit switches has changed over time. Whereas limit switches were previously used for the purpose of detecting end positions, today they are increasingly assuming functions designed to protect persons and products in machine, equipment and plant construction. The contact rows are numbered consecutively with the allocating digit (1st digit) in actuation direction. Contacts of a switching element that belong together have the same allocating digit. The second digit is the function digit that denotes the type of contact element. 1-2 Normally-closed contact 3-4 Normally-open contact 5-6 Normally-closed contact with delayed opening 7-8 Normally-open contact with delayed closing Protection class The protection class of an enclosed device denotes the degree of protection. The degree of protection includes the protection of persons against contact with parts under voltage and the protection of equipment against the infiltration of foreign bodies and water. BERNSTEIN standard enclosures mainly correspond to protection classes IP65 and IP67. Higher protection ratings are also available for individual customer solutions. In accordance with DIN EN 60521 (IEC 529), the numerals used in the protection rating denote the following: Moulded limit switches provide protective insulation and are resistant to many aggressive chemicals and liquids. The formation of condensation water in moist environments with extreme temperature fluctuations is significantly reduced on moulded enclosures. In insulation-enclosed switches the switching elements are integrated directly in the moulded enclosure and are therefore not replaceable (complete switching devices). Metal-enclosed limit switches are able to withstand high mechanical loads, they can also be used wherever hot metal chips and sparks occur and are resistant to many solvents and detergents. The switching elements in metal-enclosed switches are often integrated in the metal enclosure as modular built-in switches. The enclosure has a VDE-compliant connection for the PE conductor. The BERNSTEIN range of safety switches offers the right solution for the most diverse applications in many branches of industry. Particularly when it comes to safety, users appreciate the fact that they are able to procure all required safety switches and receive professional advice from one source. The decisive factors governing the selection of safety equipment include the ambient conditions, installation situation and risk analysis. A switching device that can be used for safety functions is identified by the standardised symbol conforming to EN 65000-41 and EN 65000-42. The switches can, of course, also be used for pure position monitoring purposes. Safety switches are divided into two categories, Type 1 and Type 2. The difference is in the actuating elements which are completely integrated in the enclosure in Type 1 and separated from the switching element in Type 2. 1st digit Degree of protection against contact and infiltration of foreign bodies 2nd digit Degree of protection against infiltration of water Example IP65: 6 = l Complete protection against contact with components under voltage or with internal moving parts Type 1 Type 2 l Protection against dust infiltration 5 = l A water jet directed from all directions at the device must not have damaging effects l Protection against hose water 13 Common Features of Electromechanical Switches Designation The designation of BERNSTEIN switching devices comprises: l The enclosure designation of the switching device l The switching function l The type of actuator Type code of position and safety switches I88 A2Z 1) AH M12 Switch group Switching system2) Actuator Special features l C2 l U1 See Pages 72-73 l M12 connection l Ti2 l SU1 l IF l A2 l I88 l SA2 l Bi2 l E2 l ENK l SE2 l Actuator turned 90, 180, 270 l Special switching forces l Special temperature ranges l GC l Other special features on request l SN2 l ENM2 lD 1) 14 The letter Z suffix to the designation of the switching function denotes the mechanical positive opening action of the normally-closed contacts. In technical data sheets, the positive opening point is identified by the international symbol p. 2) Please refer to the following pages in the catalogue to establish which switching system can be used in the switch groups. Switching function example NC = Normally-closed contact NO = Normally-open contact U1Z SU1Z A2Z Slow-action contact, 1 NC, 1 NO Snap-action contact, 1 NC, 1 NO Slow-action contact, 2 NC 11 12 23 24 13 14 21 22 11 12 21 22 SA2Z E2 SE2 Snap-action contact, 2 NC Slow-action contact, 2 NO Slow-action contact, 2 NO 11 12 13 14 13 14 21 22 23 24 23 24 UV1Z U15Z UV15Z Slow-action contact, with overlapping contacts, 1 NC, 1 NO Slow-action contact, 2 NC, 1 NO Slow-action contact, with overlapping contacts, 2 NC, 1 NO 11 12 15 16 21 22 23 24 33 34 U16Z UV16Z Slow-action contact, 1 NC, 2 NO Slow-action contact, with overlapping contacts, 1 NC, 2 NO 11 12 23 24 33 34 The actuating forces and travel distances are subject to tolerances. These tolerances are listed in Table 1. In Type 1 and Type 2 position switches, the tolerances are independent of the switching system and switching function. Function Tolerance Switching travel Switching angle Switching force in N Actuating torque in 0.25 mm 3.5 10% 10% Table 1 15 Common Features of Electromechanical Switches p = Mechanical positive opening action The term positive opening action refers to contact separation as the direct result of defined movement of the switch actuator by means of non-sprung parts. All parts involved in contact separation must be form-fit connected. The positive opening distance describes the minimum travel distance from the start of actuation of the operating element up to the point where positive opening action of the opening contacts is completed. DIN EN 60947-5-1 defines two types of positive opening action contacts with 4 connections and double break. Type Za l Positively opening contacts not galvanically isolated Type Zb l Positively opening contacts galvanically isolated Galvanic isolation describes the isolation of electrically conducted parts by insulating material or by air gaps. In switching devices with several contact elements, galvanically isolated contact elements make it possible to switch voltages with different potential (e.g. normallyclosed contact in safety circuit, normallyopen contact for indicator). In accordance with applicable health and safety requirements, protective devices (guards) must be mounted on machines, devices and systems that perform hazardous movements. Safety switches in the form of electromechanical switching devices are predominantly used for this purpose as they offer the following advantages: l High degree of safety l Non-susceptibility to interference l Safety status easily checked on site l Rational solutions 16 Form-fit, mechanical drives or coupling elements in the form of levers, rods, gearwheels etc. are necessary to ensure optimum operation of these safety components. Switching devices that are used for safety functions must be identified with the symbol p internationally standardised in accordance with DIN EN 60947-5-1. In defining the class of switching devices, this symbol denotes two important properties that must be met for personal protection applications: l Mechanical positive opening action l Disruptive breakdown voltage > 2.5 kV Disruptive breakdown voltage In accordance with DIN EN 60947-5-1, the open contacts must be able to maintain a minimum surge voltage of 2.5 kV without disruptive breakdown. Insulation-Enclosed Limit Switches I88 Recommended use Thanks to its standard dimensions as well as its wide range of contacts and actuators, this switch can be used on safety facilities and for position monitoring in virtually any industrial application. Product advantages Installation advantages zz Standard switch conforming to DIN EN 50047 zz Snap-on cover can be released with screwdriver zz Standard actuator conforming to DIN EN 50047, Type A, B, C, E zz Cover opening range 135 (cover can also be detached from hinge) zz Protection class IP65 to VDE 0470 T1 zz Enclosure and cover PA 6, self-extinguishing (UL-94-V0) zz Actuator can be repositioned by 4 x 90 zz Cable entry M20 x 1.5 zz Connection designation conforming to DIN EN 50013 Fig. 1 zz Cover protects switching element during installation zz Screw connections with self-lifting clamping plates zz Easy-action cover lock (close and press) zz Cover additionally secured with screw Fig. 2 Options zz Available with M12 connector zz AS interface variants available zz Cable entry M16 x 1.5 Design layout zz Slow-action and snap-action contacts zz Versions: 1 NC/1NO, 2 NC, 2 NO, overlapping contacts zz All NC contacts with p in the circuit diagram are positively opening contacts zz Type: Zb (galvanically isolated changeover contact) zz Latching function on request Mounting zz Two M4 screws (distance between centres 22 mm), adjustment with slots zz Two M5 screws for safety applications without additional fixing element (Fig. 1) zz Additionally secured by guide plate for lateral approach forces (Fig. 2) 32 zz Front mounting (depending on type, Fig. 3) Fig. 3 Technical data Electrical data Rated insulation voltage Conventional thermal current (up to) 1 Rated operating voltage Utilization category (up to) 1 Short-circuit protection (up to) 1 Protection class Ui max. 250 V AC Ithe 10 A Ue max. 240 V AC-15, Ue/Ie 240 V/3 A Fuse 10 A gL/gG II, Insulated Mechanical data Enclosure material Ambient temperature Mechanical service life (up to) 1 B10d (up to) 1 Switching frequency Type of connection Conductor cross sections Cable entry Thermoplastic, glass fibre-reinforced (UL 94-V0) -30 C to +80 C 10 x 106 switching cycles 20 Mio. 100/min. Screw connections Single-wire 0.5 - 1.5 mm2 or Stranded wire with ferrule 0.5 - 1.5 mm2 1 x M20 x 1,5 Standards VDE 0660 T100, DIN EN 60947-1, IEC 60947-1 VDE 0660 T200, DIN EN 60947-5-1, IEC 60947-5-1 1 Depending on switching system. See Table on Pages 76-79. W (Form B) RIWK (Form C) 10 (0.39") 85.5 26.5 (1.04") 20 (0.78") 3 (0.13") Switching operation Slow-action Snap-action Slow-action Snap-action 1 NC / 1 NO contact 6086103008 I88-U1Z W 6086153012 I88-SU1Z W 6086117017 I88-U1Z RIWK 6086167018 I88-SU1Z RIWK 2 NC contacts 6086803013 I88-A2Z W 6086817087 I88-A2Z RIWK 2 NO contacts 6086803014 I88-E2 W 6086817071 I88-E2 RIWK 1 NC / 1 NO contact Overlapping 6086303011 I88-UV1Z W Approvals U U Replacement actuator: - Replacement actuator: 3918161672 Special features/variants (on request) Special features/variants (on request) zz Available with black enclosure zz Available with black enclosure zz With latching function and following contacts: 2 NC /1 NO contact 1 NC /2 NO contact zz With latching function zz Both with and without overlap (3.37") O10 (0.39") 10 (0.39") 74 (2.91") O8 (0.31") zz With steel roller and following contacts: 2 NC /1 NO contact 1 NC /2 NO contact zz Both with overlap 33 I88 RIWL KNW RO22 10 (0.39") O14 3 (0.13") 92 (3.62") 31 (1.22") (0.55") Slow-action Snap-action Slow-action Snap-action 6086167051 I88-SU1Z RIWL 6186127112 I88-U1Z KNW RO22 6086177053 I88-SU1Z KNW RO22 21 - 22 13 - 14 13 - 14 21 - 22 Switching operation 0 mm 7N 2,5 1 NC / 1 NO contact 6086117050 I88-U1Z RIWL 5,5 7,8 4N 2 NC contacts 2 NO contacts 6086817072 I88-A2Z RIWL 6186827246 I88-A2Z KNW RO22 6086817069 I88-E2 RIWL 1 NC / 1 NO contact Overlapping Approvals U Replacement actuator: 3918161673 Replacement actuator: - Special features/variants (on request) Special features/variants (on request) zz Available with black enclosure zz With latching function zz Available with different actuating directions zz With steel roller 34 U HW RO11 (Form E) AH (Form A) 49 10 (0.39") 5.5 (0.22") 47 (1.86") (1.92") (0.71") 8 (0.31") O25 8 (0.31") O18 (0.98") 106-142.5 (4.17"-5.61") 108 (4.25") 21 (0.83") 19.5-55 (0.77"-2.16") 21 (0.83") 90 (3.54") 24 (0.94") 30.5 (1.20") O11 (0.43") AV Snap-action Slow-action Snap-action Slow-action Snap-action 6086121021 I88-U1Z HW RO11 6086171022 I88-SU1Z HW RO11 6086135033 I88-U1Z AH 6086185034 I88-SU1Z AH 6086136037 I88-U1 AV 6086186038 I88-SU1 AV 11 - 12 21 - 22 Slow-action 0 6086821099 I88-A2Z HW RO11 6086835059 I88-A2Z AH 8Ncm 20 6086836131 I88-A2 AV 35 45 45 80 6086821068 I88-E2 HW RO11 6086835116 I88-E2 AH 6086321100 I88-UV1Z HW RO11 6186335628 I88-UV1Z AH U U U Replacement actuator: 3918191547 Replacement actuator: 3918351166 Replacement actuator: 3918360984 Special features/variants (on request) Special features/variants (on request) Special features/variants (on request) zz Available with black enclosure zz Available with black enclosure zz Available with black enclosure zz With steel roller zz Available with different actuating directions zz Various actuating directions zz With steel roller zz Cranked or straight lever zz Various roller diameters zz Various roller diameters zz Cranked or straight lever zz Various lever lengths zz Various roller diameters zz Various lever lengths zz With roller over switch 35 I88 DGHW RO22 DGKW RO22 6-12 18-24 (0.24"-0.47") 5 9 (0.35") 10 (0.39") 5 21 (0.83") (0.20") O22 (0.87") 105.5 (4.15") Switching operation Slow-action Snap-action Slow-action Snap-action 1 NC / 1 NO contact 6086121029 I88-U1Z DGHW RO22 6086171030 I88-SU1Z DGHW RO22 6086127025 I88-U1Z DGKW RO22 6086177026 I88-SU1Z DGKW RO22 2 NC contacts 6086821120 I88-A2Z DGHW RO22 105.5 (4.15") 40.5 (1.59") (0.20") 40.5 (1.59") O22 (0.87") (0.71"-0.94") 10 (0.39") 2 NO contacts 1 NC / 1 NO contact Overlapping 6186321244 I88-UV1Z DGHW RO22 Approvals U Darg for Replacement actuator: 3918211529 Replacement actuator: 3918271528 Special features/variants (on request) Special features/variants (on request) zz Available with black enclosure zz With latching function zz Available with different actuating directions zz Various roller diameters and with following contacts: 2 NC /1 NO contact 1 NC /2 NO contact Both with overlap zz Various roller diameters 36 U FF KS W RAST Withdraw actuatorn Insert actuator Slow-action Snap-action Slow-action Snap-action Slow-action Withdraw a c tuator 6186140217 I88-U1 FF 6086190078 I88-SU1 FF 6186103005 I88-U1Z W RAST 6116819140 I88-U1Z KS Latch Insert a c tuator 6186803155 I88-A2Z W RAST Latch U U Replacement actuator: 3918401031 Replacement actuator: - Replacement actuator: - Special features/variants (on request) Special features/variants (on request) Special features/variants (on request) zz Available with black enclosure zz Various spring lengths zz Different spring versions or spring rod 37