Maxitrol SC11S Installation Manual
SC11S and SC25S Signal Conditioners
INSTALLATION INSTRUCTIONS
Terminals
24 VAC
Terminals 1 & 2
Modulating
Gas Valve
Terminals 3 & 4
Input Signal
Terminals 5 & 6
Note Polarity
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DESCRIPTION
SC11S and SC25S:
The SC11S and SC25S analog signal conditioners
convert a 0-10 VDC or 4-20 mA control signal to an output
level capable of driving one or more Selectra modulating
gas valves. A 3-position DIP switch configures the
SC11S or SC25S for a 0-10VDC or 4-20mA input signal.
A timer circuit initially xes the modulator output to 0 VDC
or 20 VDC whenever 24VDC is applied to the SC11S
or SC25S. After the start time interval has elapsed, the
modulator output voltage is proportional to the control
signal input. The start time interval is user selectable
between 5 and 30 seconds.
SC25S Only:
The SC25S also monitors and limits minimum and
maximum discharge air temperatures. The SC25S
senses the discharge air temperature using a TS194 (Q)
sensor w/ MT mixing tube. If the sensed discharge air
temperature approaches the set minimum or maximum
limit, the SC25S will override the control signal and
reduce DC voltage (high limit) or increase DC voltage
(low limit) in order to maintain discharge air temperatures
between the set limits. When measured discharge air
temperature is between the limit settings, the DC output is
a function of the control signal (4-20 mA, 0-10 VDC) only.
Control Input
Start Voltage
Setting
Min DA Limit
Settings
Max DA
Limit Range
Settings
TS194Q
Sensor
Max DA Adjustment
Start Time Adjustment
Actual Size: 7.5" L x 3.38" W x 2" H
SPECIFICATIONS:
Power Voltage: 24 VAC, 50/60 Hz
Control Input: 4-20 mA or 0-10 VDC
(Note Polarity) (user selectable DIP switch)
Output: 0-20 VDC, 1.8A max load
Start Time: 5 to 30 seconds nominal
(user adjustable dial)
Connections: ¼" Quick Connect Tab
Mounting: Snap Track w/Screws
READ PRIOR TO INSTALLATION:
To Avoid Internal Damage to Signal Conditioners
Follow These Guidelines.
1. Transformer secondary must not be grounded
in any portion of the circuit external to the signal
conditioner. A separate, independent transformer
is recommended.
2. Multiple signal conditioners controlled by a signal
source with common outputs (terminals 5 & 6)
require separate transformers for each signal
conditioner.
3. Multiple signal conditioners powered by a single
transformer require independent signal inputs
(terminals 5 & 6) to each signal conditioner.
© 2008 Maxitrol Company, All Rights Reserved.
1
SC11S and SC25S Signal Conditioners
INSTALLATION INSTRUCTIONS
JUMPER SETTINGS
SC25S Only:
J1 J1 J1
J2 J2 J2
Max DA Limit Range Settings:
80ºF - 130ºF nominal
110ºF - 160ºF nominal
150ºF - 200ºF nominal
150ºF - 200ºF
110ºF - 160ºF
80ºF - 130ºF
Min DA Limit Settings:
40ºF, 50ºF, or 60ºF
60ºF
50ºF
SC11S and SC25S:
J3 J3 J3
Maxitrol Company
23555 Telegraph Rd., P.O. Box 2230
Southeld, MI 48037-2230 U.S.A.
SC11S_25S_MS_EN_04.2008
40ºF
0 Voltage Start
20 VDC Start
Disabled
Start Voltage Selection:
20 VDC (xed), 0 VDC
2
© 2008 Maxitrol Company,
www.maxitrol.com
All Rights Reserved.
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