DESCRIPTION
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Electrical system
Function
In the electrical diagram, there are jumpers on terminal
blocks 8-9 and 5-6. An external thermostat and humidistat
can be connected to these terminal blocks. For more
information about this, see “Installation”. The information
below refers to the machine without these components.
When the control system is powered up, the following
things happen:
1. The contactor (K1) starts the fan (M1) and the
heating coil (E).
2. When the pressure in the cooler circuit reaches the set
interval, K2 is activated via K1 and K4 and starts the
compressor (M2).
3. Once the temperature has risen to the set value,
GT 1 disconnects the power to the heating coil (E).
4. The temperature is controlled by the thermostat
(GT1), which connects the heating coil (E) as ne-
cessary, according to the set value.
5. When the temperature of the evaporator drops, there
is a risk of frosting. If frost forms, GP disconnects
the power to K4 (resulting in defrosting), causing the
compressor to stop.
6. When the pressure switch GP and the relay K4 are
switched on, the dehumidier starts.
High pressure warning light (H1)
If the temperature becomes too high during operation,
the pressure in the condenser will rise and the high-
pressure contacts in the pressure switch (GP) will switch
over. The high pressure warning light (H1) will light up
and the compressor (M2) will stop. GP is reset with GP1.
Low pressure warning light (H2)
H2 lights up when the following prerequisites are met:
• When the low pressure in the vaporiser is below the
set value. (2.0 bar, ∆ p=1.5 bar).
Fan (M1)
The fan motor has no separate automatic circuit
breaker. Instead, it is equipped with a thermal switch.
The thermal switch is located inside the motor winding,
and disconnects the power if the motor overheats.
The thermal switch resets automatically when the
temperature returns to normal. A capacitor is used to
ensure that the fan works correctly.
Time relay (T1)
Ensures that defrosting takes place at low ambient
temperatures. This function is disabled by disconnecting
the jumper between 10 and 11 on terminal block X.
Compressor (M2)
The compressor has no separate automatic circuit
breaker. The automatic circuit breaker is integrated into
the motor windings, stopping the motor if it overheats.
The function resets automatically when the temperature
returns to normal.
Automatic circuit breaker (QF1)
Protects the compressor against overload (set value = 3.7 A).
It shuts down the whole machine if it is tripped. The
automatic circuit breaker is located inside the power
hatch. Remove the upper screws on the lter hatch.
Remove the four screws on the power hatch and open it.
The automatic circuit breaker is located under contactor
K2 behind the hatch.
Time relay (K4)
The time relay has different functions depending on
whether the dehumidier is used for drying timber or
for industrial applications (See “Industrial dehumidier”
below or “Time relay” page 23).
However, its function is always to delay the start.
Thermostat (GT1)
GT1 controls the heating coil (E) and can be set from
0-50°C.
Overheating protector (GT2:1 and GT2:2)
GT2:1 and GT2:2 are two thermal switches located in
the heating coil (E). GT2:1 and GT2:2 disconnect the
power at 90°C and must be reset manually after the
temperature drops.
Overheating protector (GT3)
GT3 is an overheating protector located in the heating
coil which disconnects the control current to K3 at 70°C.
GT3 resets automatically when the temperature drops.
Pressure switch (GP)
Timber dehumidier/ Industrial dehumidier
GP is a double pressure switch for low and high
pressure.
The low pressure contact starts the compressor when
the pressure in the evaporator reaches 2.0 bar and stops
at 0.5 bar.
The high pressure contact stops the compressor when
the temperature in the condenser rises so that the
pressure exceeds 21 bar.
The high pressure contact is reset manually using GP1.
Industrial dehumidier
When the A 150VTI is used as an industrial dehumidier,
the low-pressure value on the pressure switch (GP) must be
adjusted to a lower setting at the user’s facility. This
setting will vary from case to case depending on the
ambient temperature in which the industrial dehumidier
needs to operate. In this application, the time relay (K4)
is used for controlling defrost time (see time relay).
Handle Area Value
1 H 1 hr
2 - 9
3 M 10 m
4 - 3.5