Tech. Explanations - Kendrion Binder

the technical background
6.3.2.3 Economy mode to reduce power
consumption
It is not always necessary to increase the linear force
during the response phase (see 6.3.2.2). There are
applications in which the holding force achieved at the
end of the response phase permits a decrease in the
power consumption and hence also the temperature of
the solenoid. Fig. 13 shows a circuit for such an
economy mode. Here, once the plunger has reached its
end position, a switch is actuated to connect a resistor
with the solenoid in series. This resistor is shortcircuited
by the switch during the response phase.
This results in the following designations:
plunger in initial position and during response time
P 1 = U · I 1 = I 2 1 · R M
Plunger in end position with power reduction
P 2 = U · I 2 = I 2 2 · (R M + R V )
U
R M
I 2 = ——— = I 1 · ———
R M + R V R M + R V
P 1 = input power s 1
R M = resistance of energisation coil
R V = series resistor
R V can be designed with a value of up to two times the
resistance of the solenoid. (The exact value must be
determined by experimentation.) Fig. 14 shows the
magnetic forces for various input powers.
6.4 Input power and ambient temperature
The input power values specified on the product data
sheets were determined for an ambient temperature of
20°C. However, the energisation coils designed for this
temperature can be operated in ambient temperatures
up to 40°C. In doing so, the maximum permissible
long-term temperature for the insulation used as given
in DIN VDE 0580 point 3.3 Tab. 1 is reached, but not
exceeded. The specified values for magnetic force and
linear work are reached at the operating temperature
and 90% of the rated voltage. The operating
temperature is the temperature during operation with
the specified data, increased by the reference ambient
temperature of +40°C.
The input power must be reduced for ambient
temperatures higher than 40°C. This also reduces the
linear work. In certain circumstances this also applies
when the solenoid is fitted to part of a machine that
reaches operating temperatures higher than 40°C. The
reduction in the input power can be achieved by way
of a special energisation coil or by operating the
solenoid with a lower voltage.
Fig. 15 shows the rated voltage, rated input power and
rated linear work in relation to the ambient
temperature for a DC solenoid.
input power adjusted to suit the ambient temperature.
For a guaranteed ambient temperature < 40°C, the
input power and hence also the linear work can be
higher than the corresponding rated value.
6.5 Switching operations for DC solenoids
The oscillograms shown in Figs 16 and 17 indicate the
typical current, voltage and solenoid travel conditions
for a DC solenoid in relation to time t when being
switched on and off. The two diagrams clearly show
the different behaviour depending on whether
switching is carried out on the DC or the AC side.
The response times specified on the product data
sheets are reliably achieved at 70% of the rated magnetic
force and at rated voltage with the solenoid at its
operating temperature.
Fig. 16 Switching behaviour with switching on DC side
Fig. 13 Circuit for economy mode
M
Fig. 14 Magnetic forces and holding forces for various
input powers P
Fig. 15 Operating modes for DC solenoids in relation to
ambient temperature
ϑ 13 = ambient temperature
U N = rated voltage
W N = rated linear work
= rated input power
P N
Line 1 shows the voltage (in %) in relation to the
ambient temperature with which a solenoid may be
operated when its energisation coil is designed for the
normal ambient temperature (as given on the product
data sheet).
Line 2 shows the permissible input power as a percentage
of the specified value when the solenoid must be
operated in an ambient temperature other than 40°C.
Line 3 shows the linear work of the solenoid for an
Fig. 17 Switching behaviour with switching on AC side
ED= coil ON time
I = current
U = voltage
s = solenoid travel
t = time
t 1 = response time
t 11 = response delay
t 12 = travel time
t 2 = release time
t 21 = release delay
t 22 = return time
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