Did You Know the UCS Series of sequencer control modules can be used for. . .
- the control of multi-stage loads from a single analog signal
- the control of a tri-state motor from a single analog signal
- ventilation fan control and alarm from multiple carbon monoxide sensors
The UCS Series can be used for these as well as other unique applications. Specific information on the three applications mentioned can be found in the following technical briefs.
Save Digital Outputs – Use the UCS Series to Control Multi-stage Applications from a Single Analog Signal.
To control sequenced loads such as multiple stages of heating or cooling from a Building Automation System, a digital output is required to turn each load (stage) on and off. In those cases (when Murphy’s Law applies) where the number of loads to be controlled exceeds the number of digital output points that are available, a UCS Series Sequencer can be utilized to control multi-stage loads and save digital outputs. The relays of the UCS can be set to energize in sequence as a single analog output signal from a BAS controller increases. See the following example which shows four stages of electric heat controlled with a UCS-421 and a 2-10 VDC analog output from a BAS controller.
Wiring:
Note: When powering the UCS from 24 VAC, a separate dedicated transformer is suggested. Otherwise, exercise caution when powering multiple electronic devices from a common transformer.(See 20/20 Insights, April ’94.)
Jumpers:
For this application, set the UCS “Mode” jumpers “H1” and “H2” to the “SEQ” positions. This configuration will allow all of the UCS relays to energize as the input signal increases. The “Input Type” jumper should be placed in the “H4(V)” position for a 2-10 VDC input.
Calibration:
The UCS relays “A “, “B “, “C ” and “D ” come preset from the factory to energize or ‘make’ in sequence at 3, 5, 7 and 9 volts respectively. If the BAS controller can be programmed to work with these relay setpoint values, no further calibration of the UCS is required. If the application or type of control algorithm used by the BAS controller requires other setpoint values, each relay should be re-calibrated accordingly. See the Kele catalog or UCS product data sheet for the relay calibration procedure.
Analog to Tri-State – Use the UCS Series to Control a Tri-state Motor from a Single Analog Signal.
When the need arises to control tri-state (floating) motors from a Building Automation System, but there are no tri-state points available at the controller, consider the UCS-221 Sequencer to convert an analog output of 2-10 VDC or 4-20 mA to a tri-state signal. The following example shows a tri-state (floating) damper actuator controlled from a UCS-221 and a 4-20 mA analog output from a BAS controller.
Wiring:
Note: When powering the UCS from 24 VAC, a separate dedicated transformer is suggested. Otherwise, exercise caution when powering multiple electronic devices from a common transformer. (See 20/20 Insights, April ’94.)
Jumpers:
For this application, the “Input Type” jumper should be placed in the “J4(MA)” position for a 4-20 mA input. The UCS “Mode” jumper “J1” should be in the “FLT” position. This configuration allows the UCS “A” relay to energize on a decrease of the input signal. The “B” relay always energizes on an increase of the input signal. When the “A” and “B” relay contacts are wired as shown above, tri-state control is possible.
Calibration:
Since the UCS relay “A” is jumpered to energize on a decrease of the input signal, its’ setpoint must be adjusted to a value less than the setpoint of relay “B” to achieve tri-state control. For example, relay “A” might be set to energize when the input signal goes below 8 mA (actuator drives counter-clockwise) and relay “B” set to energize when the input signal rises above 12 mA (actuator drives clockwise). When the input signal is in the deadband between 8 and 12 mA, both “A” and “B” relays are de-energized (actuator does not change position). The actual relay setpoints (and deadband) can be varied according to the application and the type of control algorithm used in the BAS controller. See the Kele catalog or UCS product data sheet for the relay calibration procedure.
Multi-Point “CO” Monitoring and Ventilation Control – Use the UCS Series to provide Fan Control and Alarm from Multiple Carbon Monoxide Sensors
An ideal application of the UCS-221 is the control of a ventilation fan based on the input of multiple carbon monoxide (CO) sensors. In the following example four WCO-1B “CO” sensors are continuously monitored by a UMM-1 High Signal Selector. The highest signal from the WCO-1B’s (greatest concentration of “CO”) is selected and repeated as the output of the UMM-1 and input to the UCS-221. Relay “A” of the UCS-221 is calibrated to energize at a given “CO” PPM threshold, turning on a ventilation fan. Relay “B” is set to energize at a higher PPM level and serves as a high limit alarm.
Wiring:
Note: Because the power terminals on the WCO-1B’s are internally isolated from the signal terminals, and both the UCS and UMM have a shared power and signal “common” terminal, a single transformer can be used to power all of the devices as shown. Separate transformers could also be used if this presented a more practical installation.
Jumpers:
For this application, the “Input Type” jumper should be placed in the “J4(MA)” position for a 4-20 mA input. The UCS mode jumper “J1” should be in the “SEQ” position allowing both UCS relays to energize as the input signal increases. The UMM should be configured for the high signal selection mode. See the Kele catalog or UMM product data sheet.
Calibration:
For ventilation to begin, the UCS “A” relay should be calibrated to energize at a “CO” PPM threshold as defined by local codes or an engineer’s specifications. The WCO-1B has a sensing range of 0 to 200 PPM with an output of 4-20 mA. To determine the equivalent mA relay setting for a given PPM value, multiply the PPM value by (20-4 mA/200 ppm) or 0.08 and add 4.0 to the result, for example, (100 ppm X 0.08 mA/ppm) + 4.0 mA = 12.0 mA. Next, calibrate the UCS “B” relay to energize at the specified alarm level. The standard UCS relay differential is 0.5 mA which equates to 6.25 PPM. To obtain a wider differential, replace the plug-in differential resistors for both UCS relays. For example, using 73.2 k ohm resistors will provide a 2 mA or 25 PPM differential. See the Kele catalog or UCS product data sheet for the relay calibration procedure and other differential resistor values.
