The ELEKTRO 1/2014 Customer information for electricians 30th Volume, 125th Edition Here, the clamping units are scorched! The whole distribution board could have been burnt! Collection of new ideas in the Electrotechnical Industry Dear reader, Proximity to electricity is an integral part of our daily lives and has the potential to profoundly affect us in many ways. Electrical faults have been identified as one of the common causes for fires in buildings. Most of these faults have been traced to loose terminations which go undetected till the damage is done. With more than 80 years of experience, we are in a good situation to caution our readers against common pitfalls and tips to ensure that you have a safe and reliable installation. Please do not hesitate to reach out to your local HENSEL specialist if you need more information. Regards, Felix G. Hensel Managing Director of Gustav Hensel GmbH & Co. KG Still a “hot” topic: If terminals get too hot Safe connection of conductors The safety of every electrical installation, including the devices installed in it, depends on terminals used millions of times for connecting cables and conductors. For example, a bad connection within the PE-link can lead to absence of the required residual current for switching off the protective device and thus personal safety is no longer guaranteed. Concerning many connections the electrician makes every day, it is often difficult to consciously be aware of the functional inter-connection between terminals, the conductors to be connected and one’s own actions. This edition of Elektro Tipp shows how screw-type terminals can be safely connected to. A bad terminal connection can cause damage... An bad terminal connection can cause damage! Different terminal technologies Terminals with screw connections Terminal 10 mm2 wired, re-wire and take a photograph Conductors are mechanically and electrically connected together using a clamping screw. Selecting the correct terminal and torque determines the level of safety of the terminal connection. Terminals with screw-less connections Plug-in terminals automatically ensure that the contact is made by the regulating force of the spring on the conductor and will therefore not be considered any further here. In the following, Elektro-Tipp is only concerned with “screw-type terminals”. How does a terminal connection become bad and what are the possible consequences? Clamping units become bad when the conductor is no longer ensuring safe current transfer. Examples of bad terminal connections: An unsuitable terminal for the conductor Terminals are established for certain specific types of conductor and crosssections. Connection of different types of conductors and cross-sections at the same clamping unit is usually not permissible. Mechanical tensions in the terminal These occur, for example, due to a lack of strain relief or not sufficient wiring spaces, particularly for conductors with a large cross-sectional area. The probable consequences: The contact begins to char and becomes a potential fire risk. A faulty terminal usually represents a high fire risk. If there is an imperfect PE conductor connection (PE) then personal safety is no longer ensured in the case of a fault! What are the characteristics of a safe terminal connection? Wrong torque If there is an excessively high torque, the terminal lacks the properties of the spring needed to produce an optimal contact pressure. What are the characteristics of a safe terminal connection? Three factors determine the safety of a connection: 1. Selecting a suitable terminal 2. Adequate wiring space and strain relief for the cable An adequately large wiring space allows the conductor to be connected pressure-relieved. The terminal connection must relieve all strain and pressure on the conductor, for example, by means of a cable gland or cable strain relief device. The conductor must be inserted into the terminal in such a way that no external mechanical effects can act upon the terminal connection. This applies for all conductors, particularly for solid conductors with a large cross-section. 3. Permanent contact pressure through an optimal torque and spring effect Ensuring the correct contact force is a basic requirement for terminals: It is generated through simple operation of the clamping screw. The contact is safe if a good connection and safe current transfer to a defined location is guaranteed with the prescribed power (optimal torque). The amount of torque required depends on the terminal construction and size. Only the correct torque guarantees reliable terminal connections! The spring tension of the contact is set by using the prescribed torque. In this way, the required contact pressure is generated and the specified spring deflection is achieved. An excessively high torque destroys the spring effect. If the torque is too low the contact pressure is not sufficient enough, and this can result in a loose connection or the contacts becoming charred. Tightening torque in the screw-type terminal Drehmoment in der Klemmschraube Traction force in clamping Zugkraftunit im Bügel Busbar The spring effect „Zugbügel“ Stromschiene Current Strom xes transfer Leiter Conductor xes n Bo nctio ble Ju ls DK Ca al Detai nic Tech inals Term mitted. not per unit is Rated clamping t cross of at one Curren ections ning carrying section l Tighte t cross-s ina y term c(Cu) differen que capacit tors Condu be tor and/or conduc ductors s to per ed tor con Rat for cop t types of ting connected ing inals ren 2 connec ty Clamp pole g term of diffe aci n per 6 mm ctin tion ts cap ctio uni 2 and Conne connec ferrule e le jun The – mm of in cab per pol Hint: ible with end es Fixed Nm typ 1 = flex 1.2 tors f inal boxes conduc of term 1-2 Type 1-3 6 sol 1-4 4 sol 1 sol 1-6 5, 2.5 5, D 922 5 1.5 sol 5, D 912 DP 902 D 902 D 9045, 5, 2 D 924 1, DP 922 6 2 DP 922 5, DE 932 6 10 mm DE 932 5, DE 934 5 – DE 934 5, KD 504 5 04 KD 502 5, KF 504 1.5 Nm DKL 5, KF 502 5, KF 904 5, 2 1-2 202 5 KF 902 5, KF WP 16 mm 1-3 WP 302 10 sol DN 203 2045, KF 1-4 63 A sol 6 WP 1 KF 3045 1-4 4 sol 2 Nm KF WP 2.5 sol 5, 1-2 K 906 5 2 5 1-4 16 s KD 506 5, KF 906 35 mm sol 1-4 506 10 2 KF 3065 1-4 102 A 6 sol KF WP 5 2-6 3 Nm 4 sol 5, K 810 f1 06 K 910 5 KKL 2.5 sol, 1-2 5 KD 510 5, KF 910 2 f1 1-4 35 s, 1 KF 510 2105, 50 mm f 1-4 25 s, 1 2 A KF WP 3105 f 150 2 s, 1-6 WP 16 10 KF f1 5, K 950 KLS 1-6 12 Nm 10 sol, 5, K 825 K 925 5 6 sol 1-4 5 KD 525 5, KF 925 2 1-4 50 s KF 525 50 mm s 1-4 35 2 150 A 1-6 25 s 12 Nm 25 16 s 4 KLS K 950 1-4 2 1-4 50 s 70 mm 1-4 35 s 2 216 A 5, s 1-6 25 5, K 950 10 Nm 16 s 5, K 935 5, K 705 5, KF 950 1-4 50 5, KLS 2 KF 935 5, KF 550 5 1-4 70 s 70 mm KF 535 5, KD 435 s 1-4 50 4 KD 535 216 A 1-4 35 s 1-4 10 Nm 25 s 4 K 700 16 s 1-4 S 51 permitted. g unit is not Hensel provides information about the torque Rated in Nm for nt rreall u C g in n screw-type crossterminals Tighte carrying e ction of u secatalogue. in its main torq capacity terminal ne clampin ections at o rent cross-s g Aluminium conductors place special demands on a terminal and on pre-treatment of the conductors. Selecting the correct terminal according to the type of conductor and cross-section. Solid, stranded or flexible conductors have a different contact behaviour. The connectable nominal cross-section can be taken from the marking on the terminals. ConducRated tors to be connecting connected capacity per pole 2 mm and types of 2 Summary: A terminal connection is safe if all three factors mentioned are observed Terminal connections, as well as the whole electrical plant, must be checked regularly. KV Small-type distribution boards up to 63 A, 3 to 54 modules, IP 54- 65 Check regularly Inspection intervals Terminal connections must be checked Electrical installations must be checked at regularly, as well as the entire electrical regular intervals so that any defects can system. be identified and eliminated. Depending In this way the electrician is also ensuring on the devices and terminals used, the the safety and reliable operation of the inspection intervals may be different. electrical installations over the long-term. Thus, terminals of aluminum conductors Distribution boards Combinable enclosure system with door up to 250 A, IP 66 Phone: +91-44-3727 0202 Fax: +91-44-3727 0200 Email: info@hensel-electric.in ∙ www.hensel.in DK Cable junction boxes 2 1.5 to 240 mm , IP 54-67 checks than terminal connections of Mi Distribution boards up to 630 A, IP 54-65 copper conductors. (See also ElektroTipp 2/2013 Professional Connection of Aluminium Conductors) . The ELEKTRO More information about Customer Informat ion for Electro-technica l Specialists service intervals can be We can also connect aluminum conductors in this terminal? 2/2013 Why? Do we have to note something special? Cable entry systems Dear Reader, ideas in the Electrotechnic al Industry found in the Installation Collection of new and Maintenance The higher the price for copper rises, the more people in the electrical component business look for a possible substitute for this increasingly expensive raw material. When it comes to cables, people are turning to aluminum conductors with larger cross-section s. In this edition of Elektro Tipp we will deal with the professional connection of aluminum cables. It requires special installation expertise and of course the right cable junction boxes with terminals for aluminum and copper conductors. Hensel has offered a complete range of products for this very purpose for years and they have proven very reliable and can also help produce reliable connections with aluminum cables when the instructions are followed. We believe that we have once again proven our skill in the connection of cables and conductors and have helped electricians to solve often urgent problems with our range of products and services. We look forward to working with you in the future. Manual of the equipment manufacturers. Felix G. Hensel Managing partner of Gustav Hensel GmbH & Professional Connection of Aluminum Conduc tors Special expertise : is needed! To save money, more and more Most devices and people are thinking terminals are about using designed aluminum cables only for connectin instead of copg copper cables. per. It is especially Therefore special true of wires requireme with larger cross nts need to be adhered sections. to with aluminum conductors. Co. KG Construction board panels up to 630 A, IP 44-65 How can aluminum cables be properly connect ed? Sunguvachathram - Walajabad Road 4th km behind Samsung/Flextronics Sriperumbudur - 631 604 ∙ Kanchipuram Dist, Tamil Nadu need special expertise and different PASSION FOR POWER. Three Factors Determine a Safe Terminal Connection 1. The suitable terminal n the material of the conductor and its insulation n the number and shape of the wires forming the conductor (identical for each clamping unit) More detailed information on this theme Proceed to download at www.hensel.in! Practical working aid for electricians in poster formate. Type Shape solid (sol) round conductor / solid sector shaped conductor /solid stranded (s) round conductor / stranded sector shaped conductor / stranded rigid [r] flexible (f) Hint: Terminals without marking „r“ (rigid conductors only), „f“ (flexible conductors only), „s“ or „sol“ (solid conductors only) can be used to connect all types of conductors. Pole with one clamping unit Pole with two clamping units - only the same cross section and cable type per clamping unit Labelling with max. number and diameter of conductors to be connected per pole 2. Adequate wiring space Too small wiring area n Bending radius of the conductors is too small Adequate large wiring area n no mechanical stress of the terminals n additional strain relief n Conductors standing inclined to the terminal 3. The optimum torque Effects with terminals with steel body Only the correct torque guarantees reliable terminal connections! Nm Tightening torque in the screw-type terminal Terminals for incoming cables F Traction force in clamping unit Elasticity Terminals for incoming cables Busbar 2-5-pole, for copper and aluminium conductors, zum Einbau in Mi-Leergehäuse Größen 2 bis 8, fixed on mounting plate 300 x 300 mm, with Befestigungsschrauben. Mi VE 120 4-pole Mi VE 125 5-pole Mi VE 240 4-pole Mi VE 245 5-pole Rated connecting capacity 150 mm2 150 mm2 240 mm2 240 mm2 Current carrying capacity Mi VE 302 2-polig Mi VE 303 3-polig Mi VE 304 4-polig 300 mm2 300 mm2 mm2 mm2 300 mm2 630 A 630 A 630 A Tightening torque 20 Nm 20 Nm 40 Nm 40 Nm 50 Nm 50 Nm Clamping units per pole 250 A 2 250 A 4 400 A 2 400 A 4 2 50 Nm 4 Current transfer Conductor Gustav Hensel GmbH & Co. KG · D-57368 Lennestadt · www.hensel-electric.de Examples to tightening torques: labelling of terminal, specifications in the Hensel main catalogue HEI, INDIA Delivery in India via Hensel authorized distributor network ­spanning 130 cities and industrial centers. Delivery in South East Asia via Hensel authorized distributor network in all ASEAN countries. Delivery in Middle East via Hensel authorized distributor n ­ etwork in all GCC countries. R. Rajesh Managing Director Hensel Electric India Pvt Ltd info@hensel-electric.in www.hensel.in Hensel Electric India Pvt Ltd Industrial Electric Power Distribution Systems 35 Kunnam Village Delivery only via electrical wholesalers! Photovoltaik distributors that meet the standards n the cross-section of the conductor (identical for each connection) n the number of conductors to be connected with each other (see terminal labeling) Overview of types and shape of conductors