Operating Instructions
REOTRON MEW
REO
UK LTD
4
ELEKTRONIK
ELEKTRONIK
ELEKTRONIK
ELEKTRONIK
1.0
General
The range of REOTRON MEW Thyristor Regulators are microprocessor based units for controlling
the power to resistive and inductive loads. In essence the units comprise inverse parallel connected
power semiconductors (thyristors) and the control and regulation electronics. The units have a
regulated, AC output. The inverse parallel connected thyristors operate as contact free, power
controllers using the phase angle control or the full wave principles. In the phase angle control mode
(symetrical load) the equipment can be used as a voltage or current regulator and also there is an
option for power regulation. The set point value for the current and voltage can be provided by an
external control voltage of 0-10 V, 0-20 mA, DC or a potentiometer. The lowest set point has priority.
The effective value is fed back internally from a voltage or current transformer. The maximum current
limit of the unit cannot be exceeded in all regulation modes, using phase angle control. Applications
with a wide load resistance variation Rcold/Rwarm are possible, and an overloading of the unit is
prevented.
Typical Applications
Industrial
Ovens Steam
Generators
Lighting
Installations
Infra Red Emitters (Dryers)
Preheating Plants
Air Conditioning Plant
Tunnel Heaters
Room Heating Equipment
Fan Heating Systems
Plastic Moulding Equipment
Extruders
2.0 Function description
The MEW thyristor control unit was designed to operate with a
symetrical load. They include a voltage and current regulator.
In the voltage regulation mode the output voltage determined
by the set point is held constant by an internal circuit, therefore
load or mains variations have no influence on the output
voltage. The selected maximum current, however, cannot be
exceeded in this mode (current limiting). If the unit is used as a
current regulator then the output current of the unit is
compared with the setpoint and regulated accordingly. The
output voltage can increase to the selected voltage set point.
LED's illuminate if the limit Imax or adjustment limits are
exceeded.
If both set points are adjusted during operation, the regulator
always gives the lower set point priority. During voltage
regulation, with underlying current regulation, the voltage
regulation is always in operation providing the allowed current
limit is not exceeded. If the current limit is reached then the
current regulator has priority. Should the unit be used as a
pure voltage or current regulator, the other available set point
must be linked to the reference voltage (10V DC).
Actual
Current
Actual
Voltage
Current
Setpoint
Voltage
Setpoint
Enable
Fault
PULSE
GENERATION
Actual
Output
(Option)
Control
Electronics
L1
L2 (N)
F1
R
C
Mains connection
Output
I
U
