The valve electrically operated installment is realizes the
valve program control, automatic control and controls remotely the
essential equipment, its rate process may by the travelling schedule,
the torque or the axial thrust size controls. Because the valve
electrically operated installment operational factor and the use
factor are decided by the valve type, the equipment work standard and
the valve on the pipeline or the equipment position, therefore,
correctly chooses the valve electrically operated installment, to
prevented appears the excess load phenomenon (work torque to be higher
than control torque) to be very important.
Usually, correctly chooses the valve electrically operated
installment the basis as follows:
The operation moment of force operation moment of
force is chooses the valve electrically operated installment the most
main parameter, the electrically operated installment output moment of
force should for valve operation biggest moment of force 1.2 ~ 1.5
times.
The operation thrust force valve electrically
operated installment main engine structure has two kinds: One
kind does not dispose the thrust force plate, direct output moment of
force; Another kind is disposes the thrust force plate, the
output moment of force transforms through the thrust force plate in
valve stem nut into the thrust output.
Output shaft rotation 圈数 valve electrically
operated installment output shaft rotation 圈数 how many passes the
diameter, the valve lever pitch with the valve nominal, 螺纹头数
related, must according to M = H/the ZS computation (M be total
rotation which electrically operated equipment should satisfy 圈数,
H is valve opens altitude, S is valve lever transmission thread pitch,
Z is valve lever 螺纹头数).
Valve lever diameter to multi- rotations class
bright pole valve, if electrically operated installment permission
through the biggest valve lever diameter cannot through match the
valve the valve lever, then cannot the group fit out the electrically
operated valve. Therefore, the electrically operated installment
hollow output shaft inside diameter must be bigger than the bright
pole valve the valve lever outer diameter. To partially rotates
the valve as well as rotates in the valve the dark pole valve,
although does not use the consideration valve lever diameter through
the question, but when selecting and matching also should fully
consider the valve lever diameter and the key slot size, after enables
the assembly the normal work.
The output rotational speed valve opens shuts the
speed if excessively quickly, is easy to have the pressure surge
phenomenon. Therefore, should act according to the different
exploitation conditions, chooses appropriately opens shuts the speed.
The valve electrically operated installment has its special
request, namely must be able to define the torque or the axial force.
The usual valve electrically operated installment uses the limit
torque the junction box. After electrically operated installment
specification determination, its control torque also determined.
General was determining in advance in the time moves, the
electrical machinery cannot the excess load. But like has the
following situation then possibly to cause the excess load: One
is the power source electricity pulls down, cannot obtain the torque
which needs, causes the electrical machinery to stop rotating;
Two wrongly the accent decides the torque limitation
organization, causes torque which it is bigger than stops, creates
continuously has the oversized torque, causes the electrical machinery
to stop rotating; Three is the intermittent service, produces
the thermal savings, has surpassed the electrical machinery permission
warm revaluation; Four is because some kind of reason torque
limitation organization electric circuit breaks down, causes the
torque oversized; Five, the use environment hyperpyrexia,
relatively causes the electrical machinery calorific capacity to drop.
In the past carried on the protection to the electrical
machinery the means is the use fuse, has flowed the relay, the thermal
relay, the thermostat and so on, but these means respectively had the
advantages. Changes to electrically operated installment this
kind shoulders the equipment, absolutely the reliable protection means
are no. Therefore, must adopt each combination way, induces has
two kinds: One, carries on the judgement to the electrical
machinery input current fluctuation; Two, gives off heat the
situation to electrical machinery itself to carry on the judgement.
These two ways, regardless of that kind all must consider the
electrical machinery calorific capacity assigns time remainder.
Usually, crosses the load the basic protection method is:
Move the operation to the electrical machinery continuous
working or the spot the load protection, uses the thermostat;
Stops up the protection to the electrical machinery which
transfers, uses the thermal relay; To short-circuits the
accident, uses the fuse or has flowed the relay.
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