Getinge HS 6613 ER-2 - Water Level Monitoring and Protection

INTRODUCTION - 13
The task of the level device is to sense and control the water level of the
steam generator. The main components are a sensitive relay and two
electrodes, the ends of which touch the water surface at the upper and
lower fill levels. Contact of the upper electrode with the water stops the
feedwater pump, whilst absence of contact at the lower electrode starts
the pump. A third, lowest, electrode cuts off the electric power supply
to the heating elements when the electrode loses contact with water; see
boil-dry protection below.
The type and sensitivity of the level relays can be adapted to varying
water conductivity. If the feedwater is de-ionised, a high-sensitivity
level relay is required and the sensitivity setting must be increased as the
conductivity of the water decreases.
The sensitivity of the level relay is automatically adjusted at power up
to match varying conductivity.
The distance between the electrodes is another factor that affects the
overall sensitivity of the level control system.
Version with float
The GETINGE float-based level control system is intended for water
with a conductivity of 0 to 2 μS/cm, but it can also be used for higher
conductivity.
The task of the level device is to sense and control the water level in the
steam generator. The main components are a float with two level con-
tacts and two relays. The level contacts change over at the upper and
lower fill levels. The upper contact stops and starts the feedwater pump,
whilst the lower contact cuts off the electric power supply to the heating
elements; see boil-dry protection below. The purpose of the relays is to
protect the float contacts from harmful currents.
Water-level monitoring
A lamp in the “reset level” button on the steam generator control panel
is lit when the water level is correct. On some models, the water level
can also be read off on a sight glass. The sight glass has two valves
which can be closed to prevent loss of water and steam in the event of
breakage of the sight glass.
Boil-dry protection
If the water filling fails, the boil-dry protection cuts off the electric
power supply after a certain time, when the water level has fallen below
a minimum limit.
Overheat protection
This protection prevents the steam generator from overheating if the
boil-dry protection should fail to operate.