Siemens MT Series Owner's manual

Powermite 599
Technical Instructions
Document No. 155-314P25
EA 599-16
May 10, 2011
MT Series SSC Electronic
Valve Actuator, 24 Vac
Floating Control
EA1157R1
Siemens Industry, Inc.
Description 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.
Features •UL listed for plenum installations
•Direct-coupled installation without special tools (hand-tightened)
•Manual override
•Visual position indication
Application 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.
Product Numbers Table 1. Product Numbers.
Actuator Operating Mode
Actuator Prefix
Code
SSC81U Non-Spring Return
(Fail-in-Place) 259
SSC81.5U Spring Return
(Fail-Safe) 260
Ordering a Valve
Plus Actuator
Assembly
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.

Technical Instructions MT Series SSC Electronic Valve Actuator, 24 Vac Floating Control
Document Number 155-314P25
May 10, 2011
Page 2 Siemens Industry, Inc.
Warning/Caution Notations
WARNING: Personal injury or loss of life may occur if you do not perform
a procedure as specified.
CAUTION: Equipment damage may occur if you do not follow a
procedure as specified.
Specifications
Power requirements
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
10 actuators with one
transformer.
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
Functional operation
Spring return, SSC81.5U only (Figure 1, ) ≈30 s
Nominal stroke 7/32-inch (5.5 mm)
Nominal force 67 lb (300N)
Stroke/signal relationship Linear
Capacitor charge time (Figure 1 ) max. 180 sec
Spring return (SSC81.5U only) Non-mechanical, electronic returns
to stem up (0 position)
Agency certification UL UL873 Listed
cUL Certified to CSA
C22.2 No. 24-93
Ambient conditions 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)
Physical characteristics 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
Figure 10

MT Series SSC Electronic Valve Actuator, 24 Vac Floating Control Technical Instructions
Document Number 155-314P25
May 10, 2011
Siemens Industry, Inc. Page 3
Service Kits
EA1156R1
EA1162R1
EA0851R1
EA1138R1 EA1138R1 EA1138R1
411555648 For actuators with date
codes of 031215F or later.
Kit contains:
- Terminal cover
- Cover screws-2 (not shown)
- Tailpiece
- Tailpiece screw-1 (not shown)
- Cable lock
- Terminal block-3
EA0850R1
EA0851R1
411656088 For actuators with date
codes before 031215F.
Kit contains:
- Terminal Cover
- Cable lock
- Cover screw- 1 (not shown)
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
capacitor discharges (td) and the
actuator spring returns to stem up 0
position.
EA0798R2
TIME
MAX
180s. MAX 30s.
CHARGE
Max
0
NORMAL
ACTUATOR
OPERATION
ACTUATOR
POSITION
TIME TO
DISCHARGE
TIME TO
CHARGE
t0 tctntd
Figure 1. SSC81.5U Electronic Spring
Return Mechanism.

Technical Instructions MT Series SSC Electronic Valve Actuator, 24 Vac Floating Control
Document Number 155-314P25
May 10, 2011
Page 4 Siemens Industry, Inc.
Operation, Continued 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.
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:
1. Remove the terminal cover using a Phillips
head screwdriver.
2. Locate hole on the circuit board shorting
bars.
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
WIRING TERMINAL
WITH REMOVABLE
TERMINAL BLOCK
Shorting
Bars
TERMINAL
COVER
AND SCREWS
Figure 2. Manually Clearing Calibration
Stroke from Memory.
Mounting and
Installation Mount the actuator in one of the allowable positions shown in Figure 3.
EA0791R2
Figure 3. Mounting Position.
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.

MT Series SSC Electronic Valve Actuator, 24 Vac Floating Control Technical Instructions
Document Number 155-314P25
May 10, 2011
Siemens Industry, Inc. Page 5
Wiring 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.
Wiring Diagrams
NEUT
CONTROLLER ACTUATOR
EARTH GROUND
ISOLATING CLASS 2
TRANSFORMER FOR
24 Vac POWER
120 Vac
1
0
Y2
Y1
G
24
Vac
EA0795R1
Figure 4. SSC81U Neutral Switching
Non-Spring Return.
EA1234R1
NEUT
CONTROLLER
EARTH GROUND
ISOLATING CLASS 2
24 Vac TRANSFORMER
120 Vac
24 Vac
ACTUATOR
G
Y2
Y1
G0
1
0
0
Figure 5. SSC81.5U Neutral Switching
Spring Return.
Y2 Retracts actuator shaft
Y1 Extends actuator shaft
G System potential (hot)
G0 Neutral – (SSC81.5U Only)
NEUT
EARTH GROUND
ISOLATING CLASS 2
TRANSFORMER FOR
24Vac POWER
120Vac
1
0
Y2
Y1
G
24
Vac
EA0585R1
Figure 6. SSC81U Hot Switching
Non-Spring Return.
EA1235R1
NEUT
CONTROLLER
EARTH GROUND
ISOLATING CLASS 2
24 Vac TRANSFORMER
120 Vac
24 Vac
ACTUATOR
G
Y2
Y1
G0
1
0
0
Figure 7. SSC81.5U Hot Switching
Spring Return.
Y2 Retracts actuator shaft
Y1 Extends actuator shaft
G Neutral
G0 System potential (hot) -SSC81.5U Only

Technical Instructions MT Series SSC Electronic Valve Actuator, 24 Vac Floating Control
Document Number 155-314P25
May 10, 2011
Page 6 Siemens Industry, Inc.
Manual Override For manual positioning, the override knob is
in the center of the position indicator. See
Figure 8.
CLOCKWISE
EXTENDS
SHAFT
COUNTER
CLOCKWISE
RETRACTS
SHAFT
EA1161R1
A
B
AB
Figure 8. Manual Override.
Start-up Check the wiring and the position indicator
(Figure 9).
Position Indicator Output Shaft
0 Retracted
1 Extended
0
1
EA1158R1
Figure 9. Position Indicator
(Shown in 0 Position).
Troubleshooting Check the wiring for proper connections.
Service Kits If the actuator is inoperative, replace the unit.

MT Series SSC Electronic Valve Actuator, 24 Vac Floating Control Technical Instructions
Document Number 155-314P25
May 10, 2011
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.
© 2011 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
[email protected]
Dimensions
2
(48)
4.4
(110,8)
3.5
(89)
.85
(21,6)
4.5
(115,1) 5.5
(140)
EA1159R1
0
1
Figure 10. SSC Actuator Dimensions in Inches (Millimeters).
Service envelope Minimum access space recommended:
8 inches (200 mm) above the actuator and 8 inches (200 mm) beside the terminal
cover.
Document No. 155-314P25
Printed in the USA
Page 7