R-K Electronics, Inc. Protection Relays & Systems STR-12D-B

The STR-12D-B is a seal and temperature status relay for submersible pump motors, monitoring seal leakage and overheating via resistance sensing. It operates on 12VDC with pluggable terminal blocks and provides two SPDT relays rated at 5A at 120VAC, 6A at 277VAC, and 5A at 30VDC. Fault conditions trigger at 330Ω (seal) and 1,500Ω (temp-stat). The device supports 1-input or 2-input modes, with adjustable seal trip threshold from 5KΩ to 200KΩ and manual or automatic reset. Surface-mounted with epoxy fill, it weighs 1 pound and operates from -40°C to 65°C for tabs and -40°C to 60°C for terminal blocks. A 5VDC, 2mA input sense signal is used for monitoring. A 16-character, two-line backlit display indicates status, though operation may be limited below -20°C.