SMC LET-400-RDC Primary Injection Test Equipment

Primary Injection Test Equipment

The LET range addresses test applications that require high levels of AC or DC current, typically primary current injection. The generation power of the various models ranges from 1,000 to 8,000 VA or Watt.

The output voltage is adjusted by means of a variac at the primary winding of the output transformer. The injected current is measured and displayed by a built-in digital ammeter. We provide several output taps in order to better adapt the voltage range to the connected load’s impedance. This also makes adjustment of lower currents easier, while maintaining the throughput power. The integrated digital chronometer measures the time from the activation of the output until a change is detected in an external voltage or dry contact, with 1-millisecond accuracy. Some LET versions feature a motorized variac for applications that require a greater separation between the power output and the control & regulation panel.

The output transformers are especially designed and constructed to withstand maximum currents up to more than 20,000 A depending of the selected model. A built-in thermal trip protects the unit against overheating automatically. At nominal current (indicated in each model’s name), the output transformer’s temperature will stabilize itself providing continuous injection on the connected load. However, higher currents can be attained for limited periods as long as the connected load (including the test leads) falls within the unit’s output power. Please refer to the duty cycle chart of each model in this catalogue to select the one that fits your particular application best.

Every LET is supplied with standard test leads that suit the average applications. Shorter connections and/or wider sections may be required for applications that demand higher current levels. The nominal output current is tested on every production unit with the standard test leads short-circuited at their end terminals. Every unit includes all the required accessories, spare fuses, a user’s manual and a traceable certificate of calibration of the built-in instruments. The higher power units are constructed in two bodies and equipped with wheels to facilitate transportation.

Their simple, yet heavy-duty construction, compact size, reasonable weight and ease of use make the LET range one of our best-sold family of products.

Applications

Commissioning and testing of over current protections, circuit breakers, thermal and motor protections, measurement and protection transformers, interconnections, railway network applications etc.

Common Characteristics

• Control: manual.
• 3-m / 10 ft. power supply cord.
• Built-in digital ammeter, 0.5% accuracy (not included in the LET-400).
• Built-in digital timer, 1 ms resolution (not included in LET-400).
• Automatic thermal trip protection.
• Operating temperature: 0 - 55ºC / 32º - 131ºF.
• Case: robust enamelled steel.
• Built to 89/336/CEE and 93/68/CEE standard directives (CE marking).