National Instruments 779491-01 Terminal Block

Part Number 779491-01 is the identifying part number for the National Instruments CB-37F-HVD Terminal Block. The 779491-01 is a 37-pin D-SUB high-voltage DIN rail terminal block that has screw terminals for connecting up to 37 I/O signals. The terminal wire size supported by the block ranges from 12 to 30 AWG. In addition to the 37 signal screw terminals, it also features a single earth-ground screw terminal, which is not a safety ground but is used for shielding only. The maximum current supported by the terminal block is 2 A per conductor. 

The 779491-01 supports a maximum working voltage ie. the signal voltage plus the common-mode voltage of up to 150 V. Most importantly, the user must be aware that any voltages >30 Vrms, 42.4 Vpk, 60 VDC are hazardous voltages and require special safety measures when they are present. The 779491-01 measures (5.5 in. × 3.55 in. × 2.5 in.) in physical dimensions and weighs 7.5 oz. The module is recommended for operation between temperatures of 0 to 50 °C and a relative humidity of 10% to 90%. Likewise, it can be stored at a wider temperature range between  -20 to 50 °C. Furthermore, since this device is designed for indoor use only, it may require mounting inside a sealed enclosure for outside use. Moreover, the maximum altitude for the operation of the device is 2000 m. 

The 779491-01 is UL-recognized and meets the requirements of the following standards for industrial control: EN 50178, UL 508, and CAN/CSA-C22.2 No. 14. On the other hand, the user must also adopt safety measures when operating the device. First, when hazardous voltages are present, ensure that all the external wiring or any connected circuits are properly insulated from human contact. Likewise, in the existence of hazardous voltages, all the signal wires must be strain relieved and the terminal block should be placed in a UL-listed, properly-rated NEMA or IP enclosure. In addition, before beginning installation, ensure no high-voltage signals are connected to the accessory. Furthermore, only qualified technicians or service personnel must be allowed to make signal connections.