Vulcan-Hart VL3GPS Boiler User Manual


 
VL SERIES STEAMER - ELECTRICAL OPERATION
Pa
g
e 41 of 88
Electro Mechanical - Auxiliary Low Level Cut-Off
This control serves as a safety backup to the main low level cut-off (LLCO) control to meet Cal-Code
requirements. The operation of the auxiliary control is identical to the main low level cut-off control but performs
a sin
g
le function: 1) Provide auxiliary low level cut-off protection to shut off the heat source in case the water
level drops below the low level cut-off (LLCO) probe. A sin
g
le LLCO probe identical to the LLCO probe on the
main low level cut-off control is connected to the auxiliary control.
The auxiliary control is powered by input volta
g
e (120VAC) on terminals 1 and 2 which also connect to the
primary side of the internal transformer. The transformer secondary windin
g
(300 VAC) will provide power to the
internal contactor coil throu
g
h a series path
g
oin
g
from one side of the secondary windin
g
, throu
g
h the contactor
coil, throu
g
h the water level control probe, throu
g
h the water in the boiler and to the boiler for
g
round. The other
side of the transformer secondary is attached to
g
round.
When the main power switch is turned ON, the auxiliary low level control is ener
g
ized but no switchin
g
occurs.
When the water level reaches the low level cut-off (LLCO) probe, the internal contactor coil on the low level
control is ener
g
ized, closin
g
the contacts on terminals 7 & 8. The internal contactor coil will remain ener
g
ized
until the water level in the boiler drops below the LLCO probe.
When the boiler stops fillin
g
, press the manual reset button on the boiler control box. This closes and locks the
manual reset switch contacts to ener
g
ize the heat source auxiliary control.