Page 1
Powermite 599
MT Series SSC Electronic
Valve Actuator, 24 Vac
Floating Control
Technical Instructions
Document No. 155-314P25
EA 599-16
June 7, 2013
Description
Features
Application
Product Numbers
EA1157R1
The Powermite 599 MT Series SSC81U and SSC81.5U electronic valve actuators
require a 24 Vac supply to provide a floating control signal. These actuators control
Powermite 599 MT Series valves with a 7/32-inch (5.5 mm) stroke and a threaded
valve bonnet that fits the actuators.
• UL listed for plenum installations
• Direct-coupled installation without special tools (hand-tightened)
• Manual override
• Visual position indication
The Powermite 599 MT Series SSC81 electronic actuators and MT Series valves are
used in heating and cooling applications. They are used in liquid and steam
applications. The SSC81 series accepts plenum cable or 3/8-inch flex conduit
connection.
Table 1. Product Numbers.
Actuator Operating Mode
Actuator Prefix
Code
Ordering a Valve
Plus Actuator
Assembly
SSC81U
SSC81.5U
To order a complete valve plus actuator assembly from the factory, combine the
actuator prefix code with the suffix of the valve product number. See Technical Bulletin
TB251, Powermite 599 Series MT Series Terminal Unit Valve and Actuator Assembly
Selection (155-306P25) for selection procedures.
To order an actuator only, use the product number.
Non-Spring Return
(Fail-in-Place)
Spring Return
(Fail-Safe)
259
260
Siemens Industry, Inc.
Page 2
Technical Instructions MT Series SSC Electronic Valve Actuator, 24 Vac Floating Control
Document Number 155-314P25
June 7, 2013
Warning/Caution Notations
Specifications
Power requirements
Functional operation
Agency certification
Ambient conditions
Physical characteristics
WARNING:
CAUTION:
Operating voltage 24 Vac ±20%
Frequency 50/60 Hz ±2 Hz
Power supply Earth ground isolating, Class 2,
24 Vac transformer
NOTE: Do not power more than
SSC81U power consumption 0.8 VA
SSC81.5U power consumption 3 VA at ultra cap load,
2 VA at normal operation
Running time
SSC81U 125 s ±2% at 60 Hz
SSC81.5U 125 s ±2% at 50/60 Hz
Spring return, SSC81.5U only (
Nominal stroke 7/32-inch (5.5 mm)
Nominal force 67 lb (300N)
Stroke/signal relationship Linear
Capacitor charge time (
Spring return (SSC81.5U only) Non-mechanical, electronic returns
to stem up (0 position)
UL UL873 Listed
cUL Certified to CSA
C22.2 No. 24-93
Ambient temperature
Operation 41°F to 122°F (5°C to 50°C)
Transport and storage -13°F to 158°F (-25°C to +70°C)
Ambient humidity 0 to 90% rh (non-condensing)
Media temperature 41°F to 248°F (5°C to 120°C)
Wiring Connection Plenum cable or 3/8-inch flex conduit
Weight
SSC81U 1.1 lb (0.5 kg)
SSC81.5U 1.3 lb (0.6 kg)
Dimensions See
Personal injury or loss of life may occur if you do not perform
a procedure as specified.
Equipment damage may occur if you do not follow a
procedure as specified.
10 actuators with one
transformer.
Figure 1) ≈ 30 s
Figure 1 ) max. 180 sec
Figure 10
Page 2 Siemens Industry, Inc.
Page 3
MT Series SSC Electronic Valve Actuator, 24 Vac Floating Control Technical Instructions
Document Number 155-314P25
June 7, 2013
Operation
A 24 Vac control signal to terminal Y1 extends the actuator shaft proportionately to the
length of time the signal is applied.
A 24 Vac control signal to terminal Y2 retracts the actuator shaft proportionately to the
length of time the signal is applied.
In the event of a power failure with no control voltage, the non-spring return SSC81U
will hold its last position.
In the event of a power failure, the SSC81.5U returns to the stem up 0 position. The
SSC81.5U includes an electronic return mechanism that functions as follows. See
Figure 1.
• At power-up (t0), a capacitor must
charge to its maximum capacity
(Max, tc). This will take a maximum
of 180 sec, during which time no
actuator movement occurs.
• Once the capacitor is fully charged
(tc), normal actuator operation
occurs.
• If a subsequent power failure occurs
(tn) of greater than 5 seconds, the
TIME TO
CHARGE
Max
CHARGE
0
t0 tc tn t
MAX
EA0798R2
180s.
Figure 1. SSC81.5U Electronic Spring
Return Mechanism.
NORMAL
ACTUATOR
OPERATION
TIME
TIME TO
DISCHARGE
MAX
30s.
ACTUATOR
d
capacitor discharges (td) and the
actuator spring returns to stem up 0
position.
POSITION
CAUTION:
A valve must be connected to the actuator before applying power.
If applying power to the actuator when a valve is not connected, the
actuator will respond to a control signal and the shaft will extend until it
reaches its maximum end stop. Thereafter, it will not respond to any
signal. If this occurs:
1. Disconnect power.
2. Turn the manual position indicator (See
Figure 8 and Figure 9) on
the top of the actuator to the 0 position and verify the actuator
shaft completely retracts.
3. Connect a valve to the actuator, reapply power. The actuator will
return to normal operation.
Siemens Industry, Inc. Page 3
Page 4
Technical Instructions MT Series SSC Electronic Valve Actuator, 24 Vac Floating Control
Document Number 155-314P25
June 7, 2013
Calibration Stroke
The SSC81.5U writes its calibration stroke parameters to nonvolatile memory on the
first startup of the actuator. Successive startups bypass the calibration stroke unless the
memory is manually cleared. If installing the actuator on a different valve (such as on a
replacement valve), manually clear the calibration stroke from memory as follows:
Mounting and
Installation
1. Remove the terminal cover using a Phillips
head screwdriver.
TERMINAL
COVER
AND SCREWS
2. Locate hole on the circuit board shorting
bars.
WIRING TERMINAL
WITH REMOVABLE
TERMINAL BLOCK
3. Insert and gently twist a flat-blade
screwdriver to electrically connect the
shorting bars (
Figure 2). The SSC81…
then performs a new calibration stroke.
4. Secure the terminal cover back in place.
EA1155R1
Figure 2. Manually Clearing Calibration
Stroke from Memory.
Mount the actuator in one of the allowable positions shown in Figure 3.
EA0791R2
Figure 3. Mounting Position.
Shorting
Bars
Wiring
When mounting the actuator in a plenum, the proper cable must be attached to meet
local codes. Allow 8 inches (200 mm) above the actuator and 8 inches (200 mm) behind
the cable for service.
Use earth ground isolating, step-down Class 2 transformers. Do not use
autotransformers.
Determine supply transformer rating by summing total VA of all actuators used. The
maximum rating for a Class 2 step-down transformer is 100 VA.
Do not power more than 10 actuators by one transformer. (Use 0.5 amp fuse on
secondary actuator.)
NOTE: Can be wired either neutral or hot switched.
CAUTION:
Terminals must be properly wired for correct function and full life of the
actuator.
Page 4 Siemens Industry, Inc.
Page 5
MT Series SSC Electronic Valve Actuator, 24 Vac Floating Control Technical Instructions
Document Number 155-314P25
June 7, 2013
Wiring Diagrams
CONTROLLER
NEUT
ACTUATOR
Y2
Y1
G
24
Vac
EARTH GROUND
ISOLATING CLASS 2
TRANSFORMER FOR
24 Vac POWER
0
1
CONTROLLER
EARTH GROUND
ISOLATING CLASS 2
24 Vac TRANSFORMER
24 Vac
NEUT
ACTUATOR
Y2
Y1
G
G0
0
1
0
EA0795R1
120 Vac
Figure 4. SSC81U Neutral Switching
Non-Spring Return.
Y2 Retracts actuator shaft
Y1 Extends actuator shaft
EA1234R1
Figure 5. SSC81.5U Neutral Switching
Spring Return.
120 Vac
G System potential (hot)
G0 Neutral – (SSC81.5U Only)
24
Vac
Y2
Y1
G
NEUT
EARTH GROUND
ISOLATING CLASS 2
TRANSFORMER FOR
24 Vac POWER
0
1
CONTROLLER
EARTH GROUND
ISOLATING CLASS 2
24 Vac TRANSFORMER
EA1235R1
24 Vac
NEUT
ACTUATOR
Y2
Y1
G0
120 Vac
0
1
G
0
EA0585R1
Figure 6. SSC81U Hot Switching
Non-Spring Return.
120 Vac
Figure 7. SSC81.5U Hot Switching
Y2 Retracts actuator shaft
Y1 Extends actuator shaft
G Neutral
Spring Return.
G0 System potential (hot) -SSC81.5U Only
Siemens Industry, Inc. Page 5
Page 6
Technical Instructions MT Series SSC Electronic Valve Actuator, 24 Vac Floating Control
Document Number 155-314P25
June 7, 2013
Manual Override
Start-up
For manual positioning, the override knob is
in the center of the position indicator. See
Figure 8.
Check the wiring and the position indicator
Figure 9).
(
Position Indicator Output Shaft
0 Retracted
1 Extended
COUNTER
EA1161R1
CLOCKWISE
RETRACTS
SHAFT
A
AB
Figure 8. Manual Override.
1
0
CLOCKWISE
B
EXTENDS
SHAFT
Troubleshooting
Service Kits
Check the wiring for proper connections.
If the actuator is inoperative, replace the unit.
EA1158R1
Figure 9. Position Indicator
(Shown in 0 Position).
Page 6 Siemens Industry, Inc.
Page 7
MT Series SSC Electronic Valve Actuator, 24 Vac Floating Control Technical Instructions
Document Number 155-314P25
June 7, 2013
Dimensions
3.5
.85
EA1159R1
(89)
4.4
(110,8)
2
(48)
1
(21,6)
4.5
(115,1)
5.5
(140)
Figure 10. SSC Actuator Dimensions in Inches (Millimeters).
0
Service envelope
Minimum access space recommended:
8 inches (200 mm) above the actuator and 8 inches (200 mm) beside the terminal
cover.
Information in this publication is based on current specifications. The company reserves the right to make changes in specifications and models as
design improvements are introduced. Product or company names mentioned herein may be the trademarks of their respective owners.
© 2013 Siemens Industry, Inc.
Siemens Industry, Inc.
Building Technologies Division
1000 Deerfield Parkway
Buffalo Grove, IL 60089
USA
+ 1 847-215-1000
Your feedback is important to us. If you have comments
about this document, please send them to
Document No. 155-314P25
Printed in the USA
Page 7
Loading...