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About test leads
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What was the test
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The insulation of test leads
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The connections of test leads
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Special features of the connectors on test leads
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Measurement categories for test leads
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FAQ – Frequently Asked Questions about Test Leads
What was the test
Test leads establish the electrical connection between the measuring point and the measuring instrument, thus enabling the wired transmission of measured values. Her Depending on the sizes to be measured, these cables must meet special requirements. These include low internal resistance in the milli-ohm range, safe and flexible insulation against contact and protection against the irradiation of media, which can falsify the measuring result. The touch protection not only affects the measuring line, but also the elements that make direct contact with the test tip or the measuring point. Some test lead sets include test probes.
Depending on the voltage range and/or current as well as the measuring environment, different protection requirements must be met. Conrad has test leads for currents from 0.5 amps to 32 amps and voltages from 30 volts to 1,000 volts.
The insulation of test leads
Test leads are insulated with
- Rubber for hot operating conditions, fitted on one side with IEC or earthing contact plug and on the other side with measuring connections.
- PVC for highly flexible test leads and high insulation requirements. These test leads are also available in non-slip design and with an inner color jacket that makes damage to the insulation easy to see.
- Silicone for highly flexible test leads to make them unbreakable for use at high temperatures and at low temperatures. Also available in a non-slip version and with damage detection.
The insulation is available in twelve colors or color combinations. This makes it easy to distinguish between leads and leads.
The connections of test leads
The connection of a measuring line serves either for the direct measurement of the measuring value at the measuring point or for the recording of further measuring or test probes, which are designed for special applications. A distinction is made between connection A and connection B, which are used to establish contact with the measuring point on the one hand and the connection to the measuring instrument on the other. The exact version can be found in the technical data of the respective measuring line on the product page in the Conrad shop. The display of the products can be restricted to specific connections by selection conditions.
The following connectors or connections are available:
| 4mm plug | For accepting test probes or for further connection with other test leads. |
| Alligator clip | By pulling back an insulating sheath, clamps or hooks are exposed, which can be attached to the measuring point and then hold them themselves. |
| BNC plug | Coaxial connectors with bayonet lock. Are primarily used for measurements in high frequency technology. |
| Banana jacks | Also known as a 4 mm spring plug, is a widely used plug, originally developed by the German company Hirschmann. Its name is due to the shape of the spring-loaded element, which ensures that the plug fits securely into the socket. |
| 0.64 mm socket | Standard shape for 0.64 mm pin and post attachment. |
| IEC C 13 socket | Standard connection for measuring on 230 volt cold devices. |
| Alligator clip | Also called alligator clip. For quick connection and release of electrical connections. Available in many versions (insulated and not insulated). |
| Lamella plugs 2 and 4 mm | Modified designs of the banana plug |
| MC plug/socket | A standard plug in photovoltaic systems |
| N-/SMA plug | Coaxial connectors with screw connection, waterproof |
| Probe tip | With these test leads, the test probe for connection to the measuring point is already integrated, partly with spring contact lamellae arranged behind it. |
| PG plug | For safe measurements on the 230 V mains |
| Plug 2 and 4 mm | Design similar to the banana plug, but without spring contact. |
| Warm DEVICE PLUG C 16 | Standard connection for measuring at 230 volt hot devices |
Special features of the connectors on test leads
The design of the connectors on the test leads ensures the safe connection of test elements and that the actual measuring point is reached as well as the contact protection for the person acting. The following must be emphasized:
- Sliding sleeves: Release the contact only when inserting it into the socket of a measuring point
- Angled plug: The actual measuring line is brought out of the plug by 90 degrees. Among other things, this protects the measuring line from being damaged by bending.
- Stackable: On the back of the measuring plug there is a socket of the same dimensions for connecting another measuring line without additional aids such as terminals or screw connections.
Measurement categories for test leads
The measurement category describes the permissible application areas of test leads, defined by IEC 61010-1 (safety regulations for electrical measuring, control, control and laboratory devices). Internationally, this standard is called IEC 1010.
The following categories are available:
- Cat I: Measurements on circuits that do not have a direct connection to the mains, for example, devices of protection class 3 (operation with protective extra-low voltage), battery-operated devices, car electrical systems.
- Cat II: Measurements on circuits that have a direct plug connection to the low-voltage power supply, such as household appliances, portable electrical appliances.
- Cat III: Measurements within the building installation (stationary consumers with non-pluggable connection, distribution connection, permanently installed devices in the distributor), for example sub-distribution.
- Cat IV: Measurements at the source of the low-voltage installation such as counters, main connection, primary overcurrent protection, low-voltage overhead lines or at the house connection box.
FAQ – Frequently Asked Questions about Test Leads
Which test lead is suitable for which purpose?
When purchasing, factors such as the measurement category, current and voltage range, and the environment must be taken into account in terms of temperature, chemical and physical influences. It is always advisable to take a look at the manufacturer's data sheet, which is available for download for almost every test lead. This contains detailed information on the area of application.
How can ich detect a defective measuring line?
Many test leads have an additional color jacket under the insulation, which becomes clearly visible when the insulation breaks. Breaks in the current-carrying stranded wire can become noticeable at higher voltages by crackling and/or burning smell. Another indication is that the measuring device does not display any data, but was also associated with a fault at the measuring point. In this case, the test should be repeated with a replacement test lead. A defect in the measuring instrument cannot be ruled out either.
Can a test lead be repaired?
When the insulation is opened and two individual parts of a measuring line are reconnected, the measuring and safety properties assured by the manufacturer are void, so that a new measuring line must be inserted in each case. Spare test leads should always be available.