R851 Line Voltage Step/Vernier Controller

The R851B/V series line voltage ( up to 240 V a.c.) electronic step controller is designed for cost-effective and precise control of multi-stage applications typically found in electric duct heaters and boilers. Available in four or eight stage models, the R851V can also be used in conjunction with the R810 power switch or R820 SCR power controller, which will result in a fully proportional control of the load. The R851B is specifically designed for electric boiler sequencing.

The R850 can also be used on any type of staging applications found in refrigeration or automation applications.

Features

- Microcomputer-based
- Adjustable inter-stage time delay
- Test-button to bypass time delay
- Choice of last-in first out (LIFO) or first in, first out (FIFO) configuration for even wear
- 8 stage model can be slaved to another 8 or 4 stage R850 for 12 or 16 stages maximum
- Accepts industry standard signals: 0-10 V d.c., 4-20 ma d.c., 0-135 ohm

Documentation

Product Documents

R851V-8 8 Stage Step Controller Technical Bulletin
R851B-8 8 Stage, Boiler Technical Bulletin