1. Turn skorpion air heater ON using two switches:
1.1. Switch S1 (blower) sends power to the blower and to heater switch S2.
1.2. Switch S2 (heater) sends power to the heater control circuit.
1.3. Note for heater safety S2 (heater) cannot turn ON without S1 (blower) ON.
2. Adjust airflow via a rotational air damper at the blower inlet.
3. Adjust set point (SV) with the UP/DOWN arrows on the temperature controller. Heater will ramp to temperature.
3.1. The set point temperature (SV) is in GREEN.
3.2. The process temperature (PV) is in RED.
3.3. The process temperature is measured with an internal type “K” thermocouple located at the end of an element inside the stainless housing.
4. When turning the heater off the heater power (S2) may be turned off and the blower (S1) left on to cool the heater housing assembly. This is suggested to prevent burn injury of personnel around the heater but is not necessary for safety of the heater element.
• Heater voltage is regulated by a solid state relay (SSR), which is turned ON and OFF rapidly according to the temperature controller DC OUT signal. A “zero cross” type SSR is used to minimize electrical noise.
• Heater element is protected with a resistive photo detector and a thermal resistor (thermistor) mounted at the heater inlet. These sensors are connected in parallel with the DC input signal going to the SSR.
o If the element overheats (bright orange color) the photo detector resistance decreases which reduces the control signal which, in turn, limits power to the heater.
o If the air temperature in the housing reaches an unsafe level, the thermistor resistance decreases which reduces the control signal which, in turn, limits power to the heater.
o A small fixed resistor in series with the control signal sets element and air temperature limits.
• The large black dots on the wiring diagram represent connections that are made on the internal terminal strip. The terminal strip allows the customer easy access to remove and replace the heater element and blower if necessary.
The maximum air temperature (as displayed on the temperature controller) depends on the exit configuration, and the position of the inlet air damper. The chart below shows approximately the maximum air temperature achievable in various heater configurations. Actual performance may vary slightly, particularly at reduced line voltages. A closed damper (reduced flow rate) will allow higher operating temperatures until the optical sensor detects the maximum element temperature is reached. A closed damper (reduced flow rate) will also result in a faster ramp-up time.