Siemens MT Series, SSC81.5U, Powermite 599, SSC81U, Powermite 599 MT Series SSC81U Technical Instructions

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Powermite 599

MT Series SSC Electronic Valve Actuator, 24 Vac Floating Control

Technical Instructions

Document No. 155-314P25

EA 599-16

May 10, 2011

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

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.

SSC81U

SSC81.5U

Non-Spring Return

(Fail-in-Place) Spring Return

(Fail-Safe)

259

260

Siemens Industry, Inc.

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Technical Instructions MT Series SSC Electronic Valve Actuator, 24 Vac Floating Control Document Number 155-314P25 May 10, 2011

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.

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MT Series SSC Electronic Valve Actuator, 24 Vac Floating Control Technical Instructions Document Number 155-314P25 May 10, 2011

Service Kits

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)

EA1156R1

EA1162R1

- Cable lock

- Terminal block-3

Operation

EA0851R1

EA1138R1

411656088 For actuators with date codes before 031215F. 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 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

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

capacitor discharges (td) and the actuator spring returns to stem up 0

position.

POSITION

Siemens Industry, Inc. Page 3

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Technical Instructions MT Series SSC Electronic Valve Actuator, 24 Vac Floating Control Document Number 155-314P25 May 10, 2011

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.

Calibration Stroke

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.

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.

Mounting and

Mount the actuator in one of the allowable positions shown in Figure 3.

Installation

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 Industry, Inc.

EA0791R2

EA1155R1

Figure 2. Manually Clearing Calibration

Stroke from Memory.

Figure 3. Mounting Position.

Shorting

Bars

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MT Series SSC Electronic Valve Actuator, 24 Vac Floating Control Technical Instructions Document Number 155-314P25 May 10, 2011

Wiring

Wiring Diagrams

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.

CONTROLLER

NEUT

ACTUATOR

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

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)

Vac

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

120 Vac

0 1

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

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Technical Instructions MT Series SSC Electronic Valve Actuator, 24 Vac Floating Control Document Number 155-314P25 May 10, 2011

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

Figure 8. Manual Override.

CLOCKWISE

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).

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MT Series SSC Electronic Valve Actuator, 24 Vac Floating Control Technical Instructions Document Number 155-314P25 May 10, 2011

Dimensions

3.5

.85

EA1159R1

(89)

4.4 (110,8)

(48)

(21,6)

4.5

(115,1)

5.5

(140)

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.

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

sbt_technical.editor.us.sbt@siemens.com

Document No. 155-314P25

Printed in the USA

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