Stulz E2 Series User Manual

STULZ E
2
SERIES CONTROLLER FOR PERIMETER SYSTEMS OPERATION MANUAL
12
4.0 OPERATION
4.1 General
The STULZ E
2
Series controller is designed to control an
air conditioning system in a space or process application
to temperature and humidity levels as defi ned by the user.
Conditioned air is supplied to the space as needed to maintain
the temperature/humidity control setpoints.
The controller is factory confi gured and manages inputs and
outputs based on the specifi c application and equipment being
controlled. Sensor(s) may be located in the process air inlet to
monitor return air conditions and/or located in the process air
outlet to monitor the discharge air or, installed in the conditioned
space to monitor room air conditions. The controller utilizes the
sensor inputs to determine the demand for cooling, heating,
humidification and dehumidification based on the control
setpoints. The controller determines the appropriate response
(output signals) against the sensor input signals to operate the
A/C system components.
The controller includes inputs and outputs as depicted in the unit
schematic drawing supplied with the unit. Not all the inputs and
outputs shown are utilized, therefore, only the inputs/outputs
needed for the specifi c A/C system type and application are
indicated on the drawing as enabled.
4.2 Temperature/Humidity Sensors
The controller is equipped with analog input positions for
monitoring temperature and humidity sensor(s) for automatic
operation of the air conditioner. Sensor(s) may be duct mounted
to monitor return air conditions and/or located to monitor the
supply or room air conditions for the controller to determine the
demand for heating, cooling, humidifying and dehumidifying
against the control setpoints. The controller determines the
appropriate response output signal(s) to operate the A/C
system.
4.2.1 Economizer Air Sensors
The controller may be configured to monitor an outside
air temperature and humidity sensor and a room return air
temperature and humidity sensor. The premixed air sensor
values are used by the controller to activate and control an air-
side damper for economizer operation.
4.3 Control Signals
Control and alarm recognition takes place by means of the
controller analyzing signal inputs from return air temperature
and humidity sensor(s).
4.3.1 On/Off Digital Control
Based on control inputs, the controller provides an on/off signal
to activate certain modes of operation for the air conditioner (i.e.
heater, blower, humidifi er, pump, compressor or annunciate an
operating condition status i.e. alarm condition).
4.3.2 Proportional/Integral (P/I) Control
The controller calculates proportional control output signal(s)
based on the analysis of input signals which then determines
the air conditioner's required mode(s) of operation. Signals
representing temperature and humidity are each compared by
the controller as a percentage value to the maximum control
setpoint value resulting in control output values that are directly
proportional to the input signal.
The integral value is used to gradually adjust the proportional
output when the calculated output does not move the process
variable closer to setpoint in a given period of time. Decreasing
the integral value decreases the interval for the output
corrections (speeding the rate of adjustment). Increasing the
integral value increases the interval for corrections (slowing
the rate of adjustment).
4.4 Temperature/Humidity Control
The method of operation depends on the controller's
programmed operating mode. Control takes place by means of
the controller analyzing signal inputs from return air temperature
and humidity sensor(s).
NOTE
Any sensor values the controller receives from a remote
temperature and/or RH sensor are prioritized as
secondary to those received from a return temperature/
RH sensor if controlling to the return air, or a supply
temperature/RH sensor if controlling to the supply air.
4.4.1 Dewpoint Control
The STULZ E
2
Series controller may be configured for
temperature and relative humidity or dewpoint control
for dehumidification and humidification functions. When
enabled for traditional relative humidity control, the controller
continuously monitors the selected humidity control sensors
(outdoor air or return air) to determine when to activate the
humidifi cation or dehumidifi cation modes.
When enabled for dewpoint control, the controller logically
examines the combination of temperature and relative humidity
(dewpoint) and determines the proper control of cooling,
heating, humidifi cation and dehumidifi cation to move the actual
conditions to within the boundaries of the temperature/humidity
setpoints as they would appear on a psychrometric chart (see
Figure 5). It avoids scenarios where the A/C unit might both
cool and humidify the supply air when cooling alone will achieve
the desired result.
The calculated dewpoint property is used to enable the
humidifi cation or dehumidifi cation modes which results in higher
operational effi ciency and shorter component run-times.

Stulz E2 Series Specifications

General

Brand	Stulz
Model	E2 Series
Category	Controller
Language	English