The junction box enables the quick and safe integration of multiple analog load cells into any machine for weighing. METTLER TOLEDO offers precision junction boxes for hazardous areas with ATEX and IECEx certification and for food and pharmaceutical applications where EHEDG design rules are followed and with GMP and NSF certification.
The junction box is an analog component in an analog circuit where voltage changes of as little as 0.1 µV can be very significant. The accuracy and performance of analog scales can be undermined by poorly designed junction boxes, which can be sensitive to temperature changes, have poor long-term stability, and may be unable to correct corner-load errors. A modern junction box such as METTLER TOLEDO's precision junction box line is inherently robust to these effects while reducing installation time and improving ergonomics for maintenance teams.
Precision junction boxes combine IP67 or IP69K stainless-steel enclosures with electrical components that deliver high accuracy and stability. Housing material is available in either 304 (1.4301) or 316 (1.4401) stainless steel.
In contrast to junction boxes that use trim-pots, precision discrete resistors provide much better immunity to the effects of temperature and humidity. Additionally, rotary switches select arrays of precision resistors for easy correction of corner errors, offering the same ease of use provided by trim-pots but without their inherent sensitivities. Scales equipped with precision junction boxes exhibit far superior long-term stability.
Specifications:
Parameter | Specification |
Material | rugged 316 stainless steel and FDA-certified stainless steel |
Material(optional) | polyamide (Nylon), carbon steel (zinc plated), or stainless steel |
Capacity range | SLD425/SLD525 load cells is 1,000 lb to 75,000 lb |
Advantages | discrete resistors provide high accuracy and long-term connection |
Hazardous Approvals | ATEX, FM, cFM |
Features | long-term stability and easy installation features |
IP | IP66 / IP67 (Standard) |
Conduit Openings | Multiple (e.g., 4x, 6x) with NPT or PG threads. |
Input Channels | 4, 6, 8, 10 (Typical) |
Excitation Voltage (Vex) | Matched to load cell system (Typically 5-15 VDC). |
Input/Output Resistance | Matched to system impedance. |
Cable Length Compensation | Yes, via potentiometers (pots) for each channel. |
FAQ:
Load cell summing boxes or load cell junction boxes connect numerous load cells to one signal which is then read by the indicator. These load cell junction boxes are used in scales with more than one load cell. Actually, the name summing box is misleading. A more appropriate name would be an averaging box.