Siemens Powermite 599 MT Series, Powermite 599 MT SSC81U, Powermite 599 MT SSC81.5U Technical Instructions
Page 1
Powermite 599
MT Series SSC Electronic
Valve Actuator, 24 Vac
Floating Control (3-Position)
Technical Instructions
Document No. 155-314P25
EA 599-16
August 1, 2007
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 Series MT Series SSC81 electronic actuators and MT Series
valves are used in heating and cooling applications. They are used in liquid and steam
applications that require an actuator. The SSC81 series accepts plenum cable or 3/8inch 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 Building Technologies, Inc.
Page 2
Technical Instructions MT Series SSC Electronic Valve Actuator, 24 Vac Floating (3-Position) Control
Document Number 155-314P25
August 1, 2007
Specifications
Operating voltage 24 Vac ±20%
Power requirements
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
Control characteristic
Control Signal
Y2 Retracts actuator shaft
Y1 Extends actuator shaft
G System potential
G0 (SSC81.5U only) System neutral
Functional operation
Running time
SSC81U 150 s ±2% at 50 Hz
125 s ±2% at 60 Hz
SSC81.5U 125 s ±2% at 50/60 Hz
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) with
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 5.5-in × 4.35-in × 2.0-in
(140 mm × 110,6 mm × 48 mm)
Page 2 Siemens Building Technologies, Inc.
Page 3
MT Series SSC Electronic Valve Actuator, 24 Vac Floating (3-Position) Control Technical Instructions
Document Number 155-314P25
August 1, 2007
Service Kits
411555648 (031215F): Kit contains:
- Terminal cover
- Cover screws-2 (not shown)
- Tailpiece
- Tailpiece screw-1 (not shown)
- Cable lock
- Terminal block-3
EA1156R1
EA1162R1
Operation
EA0851R1
EA1138R1
EA1138R1
EA1138R1
411656088 (031215F or later): Kit
contains:
- Terminal Cover
- Cable lock
- Cover screw- 1 (not shown)
EA0850R1
EA0851R1
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 spring returns to the stem up 0 position.
The SSC81.5U includes an electronic return mechanism that functions a s 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
Siemens Building Technologies, Inc. Page 3
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Technical Instructions MT Series SSC Electronic Valve Actuator, 24 Vac Floating (3-Position) Control
Document Number 155-314P25
August 1, 2007
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 7 and Figure 8) 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
Mounting and
Installation
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.
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.
Shorting
EA1155R1
Bars
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.
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.
Page 4 Siemens Building Technologies, Inc.
Page 5
MT Series SSC Electronic Valve Actuator, 24 Vac Floating (3-Position) Control Technical Instructions
Document Number 155-314P25
August 1, 2007
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.
CAUTION:
Terminals must be properly wired for correct function and full life of the
actuator.
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
EA1235R1
24 Vac
NEUT
ACTUATOR
120 Vac
Y2
Y1
G
G0
0
1
0
EA0795R1
120 Vac
Y2…Retracts actuator shaft
Y1…Extends actuator shaft
G System potential
Figure 4. SSC81U Non-Spring Return.
Y2…Retracts actuator shaft
Y1…Extends actuator shaft
G… System potential
G0…System neutral
Figure 6. SSC81.5U SR Hot Switch
CONTROLLER
24 Vac
EARTH GROUND
ISOLATING CLASS 2
24 Vac TRANSFORMER
EA1234R1
Y2…Retracts actuator shaft
Y1…Extends actuator shaft
G… System potential
G0…System neutral
NEUT
ACTUATOR
G0
120 Vac
Y2
Y1
G
0
1
0
Figure 5. SSC81.5U SR Neutral.
Siemens Building Technologies, Inc. Page 5
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Technical Instructions MT Series SSC Electronic Valve Actuator, 24 Vac Floating (3-Position) Control
Document Number 155-314P25
August 1, 2007
Manual Override
Start-up
For manual positioning, the override knob
is in the center of the position indicator.
See Figure 7.
Check the wiring and the position indicator
(Figure 8).
Position Indicator Output Shaft
0 Retracted
1 Extended
COUNTER
EA1161R1
CLOCKWISE
RETRACTS
SHAFT
A
AB
Figure 7. 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 8. Position Indicator
(Shown in 0 Position).
Page 6 Siemens Building Technologies, Inc.
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MT Series SSC Electronic Valve Actuator, 24 Vac Floating (3-Position) Control Technical Instructions
Document Number 155-314P25
August 1, 2007
Dimensions
3.5
.85
EA1159R1
(89)
4.4
(110,8)
2
(48)
1
(21,6)
4.5
(115,1)
5.5
(140)
Figure 9. 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. Flowrite is a trademark of Siemens Building Technologies, Inc. Product or company names mentioned herein
may be the trademarks of their respective owners. © 2007 Siemens Building Technologies, Inc.
Siemens Building Technologies, Inc.
1000 Deerfield Parkway
Buffalo Grove, IL 60089-4513
U.S.A.
Your feedback is important to us. If you have comments
about this document, please send them to
sbt_technical.editor.us.sbt@siemens.com
Document No. 155-31425
Country of Origin: US
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