Control output to manage DC contactors of a test stand

Advantages of managing the external DC contactor via BT 20000:

• Active pre-charge will prevent unwanted inrush currents when the test object gets connected
• Safer operation of the battery test stand – Safety Sense avoids faulty connections as well as polarity reverse faults
• “Zero current turn-off” on DC contactor will save the lifetime of the DC contactor

Active pre-charge prevents unwanted inrush currents

If a test object is connected to the test device, an inrush current occurs when the battery cell puts energy into the output capacitor of the test device. This is hazardous for several reasons:

• The current could damage the battery or the test equipment
• Potentially dangerous and alarming sparking at the terminal when connecting
• Existing DC contactors will wear down quickly whenever there is a peak current

Therefore, pre-charge of the output capacitor is required. BT 20000 offers an automated active pre-charge. Due to completely independent internal and external sense measurements, the device will pre-charge its internal capacitor without using any energy from the battery under test. The BT 20000 then closes the external DC contactor once the active pre-charge is finished.

Safety Sense avoids faulty connections

The safety sense is intended to be a fixed installed part of the test stand. It does not change or move around when a new test object is connected. As this part of the installation is always fixed, it is not compromised by potential operator errors such as:

• Operator might put test object and sense in reverse
• Operator might mix up different sense channels
• Sense might fall apart during test

Since the Safety Sense can detect these issues, the added benefits result in complete operational safety.