7
When the water level is at a safe level in the still
evaporator (the water level is above the immer-
sion type heaters and makes contact with the
probe), the circuit across probe terminals 1 and
2 at the terminal board (TB1) is completed. The
completion of this circuit, after a two-second
delay to prevent contactor chatter, will start the
contactor to energize the contactor coil to con-
nect the heater service to the still. Opening of
the probe circuit (water no longer makes contact
with the probe) will stop the contactor without
delay.
The Barnstead solid state low water cutoff is
designed to prevent damage caused by low
water conditions in the evaporator of Barnstead
electrically heated water stills. The low water cut-
off consists of the Barnstead Solid State Low
Water Control, a probe assembly for installation
on Barnstead stills, and still heat control (contac-
tor).
Still Heat Control
The heat control consists of a cabinetized con-
tactor designed for wall mounting. The contactor
cabinet has a removable cover and knockouts
for conduit connections. The contactor is provid-
ed to control the heat supply to the still heating
elements, as determined by the low water cutoff
controller. The contactor coil operates from a 115
VAC, 50/60 hertz, single phase electrical service
and derives its control voltage at terminals 6 and
11 at the terminal board in the low water cutoff
control cabinet. See Figure 8 for information on
the contactor size required for a given size still
and the available heating service. Unpack the
still carefully so as not to damage any of the
parts. Ensure that all parts are removed from the
container before discarding the packing materi-
als.
I
NTRODUCTION
