Siemens SSC61 HVAC Modulating Electric Valve Actuator

Product Overview

SSC61: 24 V AC/DC, 0~10 V DC modulating electric actuator, non-spring return (Fail-in-place; maintains current valve position upon power loss)

Designed for proportional flow control of chilled/hot water 2-way and 3-way valves on fan coil units, air handling units and terminal HVAC hydronic systems.

Comparison within the product series:

SSC61: 0–10 V modulating, non-spring return (no fail-safe reset)

SSC61.5: 0–10 V modulating, built-in supercapacitor, auto close-to-zero (valve shutoff) on power failure

SSC81: 24 V floating (3-position) control

SSC31: 230 V floating (3-position) control

2. Key Technical Specifications

3. Compatible Valves
4. Direct mount (no adapter required)

VVP45… / VXP45… / VMP45… (Siemens threaded 2-way & 3-way control valves)

2. Requires adapter kit ASK30

VVG45…, VXG45…, legacy Landis & Gyr X3i series valves

4. Terminal Definition & Wiring

Terminals: G, G0, Y

G / G0: AC/DC 24 V power supply

Y: DC 0~10 V modulating control signal (output from controller)

Control Logic:

Y=0 V → Valve fully closed; Y=10 V → Valve fully open; intermediate voltages correspond to linear proportional modulation

⚠️ SSC61 has no built-in valve position feedback output. Select alternative models if position feedback is required.

5. Critical Notes for Power-Up Stroke Calibration
6. The actuator must be mounted onto the valve before initial power-up. Powering up without valve load will cause permanent jamming.
7. Automatic full-stroke travel to detect upper/lower limits; calibration lasts approx. 60 s. Control signal becomes effective after calibration completes.
8. Recalibration is mandatory after actuator disassembly, re-installation or valve replacement.
9. Typical Application Scenarios

Modulating 2-way valves for fan coil temperature control, 3-way mixing valves for AHU heating/cooling coils, hydraulic regulation on compact air conditioning units, supply water modulation for radiant heating/cooling systems.

7. Model Selection Guidelines & Pitfall Avoidance
8. If automatic valve shutoff upon power loss is required: Do not select SSC61, use SSC61.5 instead.
9. If only switch control is available without a 0–10 V controller: Select SSC81 (3-position floating control).
10. Do not connect more than 10 actuators to a single transformer to avoid voltage drop and insufficient power supply.
11. Only applicable for low-pressure hot/chilled water closed systems; not suitable for steam service.
12. Common Troubleshooting
13. Actuator fails to operate

Verify 24 V power supply; confirm variable 0~10 V signal on terminal Y

Check if jammed by no-load energization: Turn manual override knob to zero position, cut power and restart for recalibration

2. Unstable modulating response

Separate signal cables from power cables to reduce electromagnetic interference; control wiring length recommended ≤50 m

3. Cannot reach full open / full closed position

Valve plug jamming mechanically; re-execute automatic power-up calibration

Engineering Application Case Collection for Siemens SSC61 (0–10 V Modulating Actuator)

Standard assembly: SSC61 + VVP45 (2-way valve) / VXP45 (3-way valve); 5.5 mm stroke, 300 N thrust, non-spring return (holds valve position on power loss); compatible with DDC or standalone room controllers with DC0–10 V output.

⚠️ Critical selection boundary: Use SSC61.5 if fail-safe shutoff is required on power loss. All cases below apply to installations without power-failure safety shutoff demand.

Case 1: 4-Pipe Fan Coil Modulating Temperature Control in Office Buildings (Most Common)

Project Overview

Multi-storey Grade A office with 4-pipe central air conditioning; high-precision zone temperature control for fan coil units, BMS DDC provides 0–10 V analog output.

Bill of Materials

Actuator: SSC61

Valves: Chilled water circuit VVP45.20-4 (DN20 2-way); Hot water circuit VVP45.20-4

Controller: Siemens DDC (PID output 0–10 V)

Control Logic

Room temperature sensor collects indoor temperature → DDC PID calculation outputs 0–10 V signal:

0V = Valve fully closed; 10V = Valve fully open. Continuous modulation of chilled/hot water flow to stabilize room temperature within ±0.5 ℃.

Rationale for SSC61 Selection

1. Stable power supply available in office buildings; low blackout risk, no requirement for power-failure reset.
2. 30-second full stroke travel meets dynamic load variation of fan coils.
3. Built-in automatic stroke calibration reduces commissioning workload for massive terminal units.
4. Compact size, suitable for confined service space around fan coil units.

Commissioning Highlights

Complete mechanical installation before energization; prohibit no-load power-up.

Maximum 10 SSC61 units per 24 V transformer to avoid voltage drop.

Separate control wiring and power wiring to prevent interference on 0–10 V signal.

Case 2: 3-Way Mixing Control for Heating & Cooling Coils on Compact AHU

Project Overview

Fresh air handling unit (AHU) for shopping mall; 2-pipe hydronic system. 3-way mixing valve stabilizes supply air temperature by regulating mixed water temperature.

Bill of Materials

Actuator: SSC61

Valve: VXP45.25-6.3 (DN25 3-way mixing valve)

Control Logic

Mixed chilled supply water and system return water via the 3-way valve. DDC adjusts valve opening according to supply air temperature to change mixing ratio and stabilize water temperature entering cooling coil.

VXP45 is recommended for mixing service only; diverting application is not advised.

Rationale for SSC61 Selection

AHU equipped with backup power; forced valve shutoff is unnecessary during short power interruption. Continuous proportional modulation delivers smaller supply air temperature fluctuation compared to on/off valves and reduces fan energy consumption.

Case 3: Radiant Cooling & Floor Heating Branch Regulation for Hotel Properties

Project Overview

Boutique hotel with ceiling radiant cooling + low-temperature hot water floor heating; independent hydraulic regulation for each guest room.

Bill of Materials

SSC61 + VVP45.15-2.5 DN15 2-way modulating valve

Process Description

Room thermostat outputs 0–10 V signal to continuously adjust water flow into radiant panels, preventing overcooling or overheating and eliminating temperature oscillation common with on/off valves.

Note

Fully compatible with glycol antifreeze media (medium temperature range 1～110 ℃).

Case 4: Reheat Coil Flow Control for Laboratory Constant-Temperature Air Handling Units

Project Overview

Testing laboratory requiring precise indoor temperature & humidity stability. Fresh air is pre-cooled by chilled water, then reheated to fine-tune supply air temperature.

Configuration

SSC61 + VVP45.20 hot water 2-way control valve

Control Features

PID continuously modulates hot water flow to compensate fresh air load fluctuation. Uninterrupted power supply in the laboratory removes the need for fail-safe shutoff; SSC61 is adopted instead of SSC61.5 to save project cost.

Case 5: Terminal Temperature Control Retrofit for Commercial Complex Heat Exchange Station

Retrofit Background

Original on/off electric valves caused large room temperature swings and frequent hydraulic shock to water pumps. Upgraded to modulating control.

Solution

Reuse existing threaded piping for direct replacement: SSC61 + VVP45 threaded valve, connected to BMS via 0–10 V analog output.

Retrofit Advantages

1. Direct nut coupling without extra adapters.
2. Manual override knob enables manual valve opening for draining during maintenance.
3. Supports multi-actuator parallel control for unified regulation of large zones.

🔴 Universal Selection Red Rules Applicable to All Cases

1. SSC61 MUST NOT be used for fire protection circuits, process safety loops or main chilled water valves in unattended mechanical rooms. Select SSC61.5 (capacitor-powered fail-safe shutoff) if valve shutoff is required upon power loss.
2. V..P45 series valves have limited maximum shut-off differential pressure; do not deploy under high differential pressure conditions.
3. Restricted to closed chilled/hot water circuits; steam service is prohibited.
4. Do not install in locations with sustained ambient temperature exceeding 50 ℃.

📌 Quick Comparison Table: SSC61 VS SSC61.5

Standard Installation & Commissioning Procedure for Siemens SSC61 Electric Actuator

Applicable to SSC61 (0~10 V modulating actuator, 5.5 mm stroke, matched with VVP45/VXP45 series control valves)

⚠️ Critical Precondition: NEVER energize actuator without valve mounting. No-load power-up leads to permanent internal mechanical jamming.

1. Pre-Installation Inspection
2. Verify model: SSC61, supply AC/DC24 V, control signal DC0~10 V
3. Inspect valve: VVP45/VXP45 valve plug moves freely without sticking; clean valve stem, remove burrs and limescale
4. Ambient confirmation: Operating temperature 5～50 ℃; keep away from steam, water dripping and intense radiant heat sources
5. Required tools: Hand-tightening only for coupling nut (wrenches forbidden); flat screwdriver for wiring
6. Mechanical Installation Steps
7. Adjust valve plug to mid-stroke position

Turn valve handwheel to extend valve stem to mid-position for smooth engagement with actuator.

2. Rotate the black lock nut at the bottom of SSC61 fully downward.
3. Align actuator vertically with valve stem and fit smoothly. Vertical upward mounting preferred; downward inverted installation is discouraged.

Horizontal side mounting is acceptable. Inverted downward mounting risks condensate ingress into actuator housing.

4. Tighten bottom lock nut upward by hand only. DO NOT apply force with wrenches.

Over-tightening damages internal actuator seals and valve stem.

5. Visual confirmation:

Actuator base fits flush against valve bonnet without tilt

Valve stem fully seated inside actuator plunger recess, no offset or binding

6. Toggle side manual override knob, test full stroke travel manually; plunger extends and retracts smoothly without abnormal friction noise.
7. Electrical Wiring (Terminals: G, G0, Y)

Terminal Definition:

G, G0: 24 V AC/DC power supply

Y: 0~10 V DC modulating control signal (output from DDC / room thermostat)

Wiring Specifications:

1. Perform wiring only when power is disconnected!
2. Shielded cable recommended for control wiring; shield grounded at single end. Separate control cables and power cables with minimum spacing ≥15 cm.
3. Do not route 230 V power cables together with 0~10 V signal cables in the same conduit.
4. Parallel installation: Max. 10 units per transformer to avoid voltage drop.

No built-in valve position feedback; no extra wiring required for feedback.

4. Power-Up & Automatic Stroke Calibration (Most Critical Commissioning Step)
5. Confirm mechanical assembly and wiring before applying 24 V power.
6. Automatic calibration sequence starts after energization (duration approx. 45~60 seconds).

Movement sequence: Plunger travels to fully closed limit → fully open limit → returns to initial position.

3. Do not feed control signal or operate manual override knob during calibration.
4. Actuator enters standby mode after calibration; 0~10 V control signal becomes active.

Recalibration mandatory if:

Actuator disassembled and re-installed

Valve replaced

Valve maintenance performed

5. Functional Test
6. Controller output Y=0V: Plunger retracts, valve fully closed
7. Controller output Y=5V: 50% mid-position
8. Controller output Y=10V: Plunger extends, valve fully open
9. Ramp control signal repeatedly; check smooth movement without jitter or abnormal noise.
10. Installation Prohibitions (Hard Rules)
11. ❌ Long-term inverted downward mounting of actuator is forbidden
12. ❌ Do not use wrenches to tighten lock nut; hand tightening only
13. ❌ No power supply without valve mounted (risk of permanent jamming)
14. ❌ Media temperature exceeding 110 ℃ is not permitted
15. ❌ Cannot be fitted onto steam valves directly
16. ❌ Power cut during calibration causes misrecognized limit positions; cut power, wait 3 minutes and restart calibration.
17. Disassembly Procedure for Maintenance
18. Disconnect 24 V power supply
19. Toggle manual override knob to retract plunger to fully closed position
20. Unscrew bottom lock nut downward by hand
21. Lift actuator vertically upward to remove

Recalibration on power-up is required after re-installation.