Description Of Components - Emerson Sempell Series Operating Instructions Manual

Sempell SerieS STe 4 ConTrol DeviCe for SafeTy valveS
Operating instructiOns

2 DeScription of componentS

For the following sections the connection
diagram section 9.2 is valid unless other
provided.
2.1 Description of the function
The type-tested control device STe 4 pilots
the on- and off-switch of the loading air or
lifting air of the spring-loaded safety valve with
pneumatic actuator.
Under power the 2/2 way solenoid valves
(Y1, Y2, Y3) are closed and the 3/2 way solenoid
valve (y4) connects de-energized the pressure
space (H) of the pneumatic actuator for lifting
air with the atmosphere.
via pressure regulator (r1), filter (f) and throttle
(D), the loading air is on the loading cavity (B) of
the pneumatic actuator. it causes an additional
closing force to the spindle of the spring-loaded
safety valve with pneumatic actuator.
The pressure gauge MB in the control unit
shows the loading pressure, the control lamps
(y1, y2, y3, B) shine.
opening
The pressure switches (D1, D2, D3) inserted
into the impulse unit are adjusted to the desired
set pressure. In case of exceeding set pressure,
the solenoid valves (y1, y2, y3) installed into
the control unit become de-energized. These
solenoid valves (Y1, Y2, Y3) switch by means of
the contacts of the relay and are assigned to
the corresponding pressure switch
additionally, each of the three solenoid valves
become simultaneous de-energized by means
of a relay contact released by each of the three
pressure switches (D1, D2, D3). The solenoid
valve (y4) is energized.
The loading air is relieved through the solenoid
valves (y1, y2, y3). The lifting air is built up by
the solenoid valve (y4). The controlled safety
valve opens.
The relief of the loading air also occurs if only
one of the three solenoid valves (y1, y2, y3)
opens.
If the lifting air is not switched on, the
controlled safety valve opens after the
reduction of the loading air like a spring-loaded
safety valve.
closing
If the system pressure drops below the reseat
pressure of the pressure switches (D1, D2, D3),
the solenoid valves (Y1, Y2, Y3, Y4) switch back.
The supply of lifting air stops. The pressure
space (H) of the pneumatic actuator relieves to
atmosphere and the loading air in the loading
cavity (B) builds up again. The controlled safety
valve closes.
Sliding pressure operation
Open the safety valve below the set pressure
by an electrical impulse from the control
D1 a1
P1 e1
room. in case of higher control air pressures
(lifting air) a second pressure regulator r2
will be used to reduce the loading air pressure
(accessory, see system circuit diagram with
pressure regulator r2).
2.2 Description of the construction
according to the specification, there are three
separated control lines in the control device
STe 4, that means three pulse generators
(pressure switches) and three control units
(solenoid valves) with each an independent
pressure sense connection.
for testing and/or repair purpose it is possible
to temporarily put one of the three control
lines out of operation by means of the valve
interlock (G).
The control device STe 4 consists of the
functional groups:
impulse unit A161, electric switch unit A162 and
pneumatic control unit a163.
The impulse unit is composed of the
connections for the pressure sense lines (e1,
E2, E3), the shut-off valves with interlock (A1,
A2, A3) and the pressure switches (D1, D2, D3).
The test connections (P1, P2, P3) are located
between the shut-off valves and the pressure
switches. The pressure switches contain two
micro switches so that opening and closing
pressure can be set independent from each
other (P-min, P-max).
attention!
The components of the impulse unit A161 are
under system pressure!
G1 D2 a2
e2 P2
G2 D3 a3
e3 P3
G3
2