Schneider NSYCCOTHO Enclosure Thermostat

Informații de bază

Numele complet: ClimaSys CC Mechanical Enclosure Thermostat (Single-circuit, Deschis normal NU)

Serie: ClimaSys CC Enclosure Climate Control Components

Aplicație: Activate cooling fans inside electrical enclosures at high temperatures; contacts close once temperature reaches setpoint to start ventilation fans.

Defalcarea codului de model

NSY: Prefix for Spacial enclosure climate accessories

CC: ClimaSys CC mechanical thermostat series

OT: Thermostat

H: Încălzire / Cooling Thermostatic Switch

O: NO = Normally Open Normally Open Contact (Blue Knob, Cooling Control)

Cross-reference within the same series

NSYCCOTHO: 1NO Normally Open → Control cooling fans (blue dial)

NSYCCOTHC: 1NC Normally Closed → Control enclosure heaters (red dial, low-temperature heating activation)

NSYCCOTHD: Dual thermostat 1NO+1NC, controls heating and cooling simultaneously

2. Specificații electrice de bază

3. Operating Logic

✅ NSYCCOTHO (Deschis normal NU)

Temperature ＞ Setpoint → Contacts close → Cooling fan starts

Temperature ＜ Setpoint → Contacts open → Fan stops

Typical setting: 35°C ~ 40°C for enclosure fan activation.

4. Instrucțiuni de cablare

Bottom terminals 1 şi 2: passive switch contacts, no separate power supply required. Wire in series within the fan control circuit.

Nota: This unit serves only as a switching signal. Do not drive high-power fans directly. An external contactor is recommended for heavy loads.

5. Scenarii tipice de aplicare

PLC control cabinets, variable frequency drive cabinets, UPS enclosures, outdoor electrical boxes

Automatic overheat cooling control for cabinet interiors

Substații, linii de producție automatizate, HVAC electrical cabinets

6. Selection Pitfalls to Avoid
7. Do not mix up OTHO / OTHC

OTHO (blue dial): NO contact → Cooling fan control

OTHC (red dial): NC contact → Anti-condensation heater control

2. Mechanical thermostats feature inherent hysteresis (4~6°C) and offer lower precision than electronic thermostats. Select electronic NSYCCOTHxx series for high-precision requirements.
3. Suitable for indoor enclosure installation only. Outdoor direct exposure is prohibited (Clasament IP20).
4. If load current exceeds 10A, an auxiliary relay or contactor must be added.
5. Alternative Upgrade

For simultaneous heating and cooling control: upgrade directly to NSYCCOTHD (dual dial, 1NU + 1NC).

Operating Principle of Schneider NSYCCOTHO Mechanical Thermostat

1. Core Sensing Element: Banda Bimetalica

Fundamental Principle

Two thin metal strips with vastly different coefficients of thermal expansion are pressure-welded together to form a bimetallic composite strip.

Metal A: High thermal expansion coefficient; Metal B: Low thermal expansion coefficient

Rising ambient temperature → Unequal thermal elongation causes the bimetallic strip to bend toward the metal with lower expansion;

Falling ambient temperature → Reverse deformation occurs.

The NSYCCOTHO relies on bimetallic strip deformation to directly actuate mechanical contacts. Fără alimentare, circuit boards or sensor chips required, classified as a passive mechanical switch.

2. Internal Structural Components
3. Temperature-sensing bimetallic strip (directly measures cabinet air temperature)
4. Adjustment screw + calibrated knob (external blue dial for threshold setting)
5. Moving contact and fixed contact (NU contacte, Terminale 1, 2)
6. Mechanical spring assembly (provides contact pressure to ensure reliable connection)
7. Complete Actuation Sequence (Focus on NSYCCOTHO Normally Open Version)

Model Feature: NO contact, designed for cooling fan control

1. Cabinet Temperature ＜ Set Temperature

Limited bending of the bimetallic strip; mechanical assembly remains released → Contacts open

Fan circuit de-energized, fan inactive.

2. Cabinet Temperature rises ≥ Set Temperature (Actuation Point)

Continuous thermal bending of the bimetallic strip generates thrust to overcome spring preload, pushing contacts closed

→ Terminals 1 şi 2 conduită, cooling fan circuit energized to start exhaust ventilation.

3. Cabinet Temperature decreases

The bimetallic strip gradually rebounds as temperature drops;

⚠️ Critical Feature: Inherent hysteresis (4 ~ 6°C)

Exemplu: Setpoint = 40°C for fan startup

≥40°C → Contacts close, fan turns ON

Fan will NOT stop at 39°C; contacts typically open at 34~36°C

Purpose of hysteresis: Prevent rapid cycling, contact chatter and arcing caused by minor temperature fluctuations. This characteristic is intrinsic to mechanical thermostats and cannot be eliminated.

4. Caracteristici electrice
5. Passive Contacts

The thermostat requires no dedicated operating power; it functions purely as a temperature-controlled mechanical switch. Circuit power is supplied externally (230VAC, 24V, etc.).

2. Evaluarea contactului: 10A/250VAC resistive load; derated to 2A/250VAC for inductive loads.
3. Principle Comparison with NSYCCOTHC (Normally Closed Heater Thermostat)

NSYCCOTHO (Blue Dial, NU): Closes at high temperature → Fan cooling control

Temperature ↑ → Circuit conducts; Temperature ↓ → Circuit opens

NSYCCOTHC (Red Dial, NC): Conducts at low temperature → Anti-condensation cabinet heater control

Temperature ↓ → Circuit conducts; Temperature ↑ → Circuit opens

Both share identical bimetallic sensing elements; only the internal contact assembly orientation differs.

6. Avantaje & Limitări (Derived from Operating Principle)

✅ Advantages

Passive, no auxiliary power; stable performance in harsh cabinet environments

Simple construction, rezistent la vibratii, gamă largă de temperatură de funcționare

DIN rail mounting with straightforward wiring

❌ Limitations (determined by bimetallic technology)

Moderate accuracy with fixed hysteresis; precise constant temperature control is unachievable

Mechanical fatigue after repeated cycling; service life shorter than electronic thermostats

No remote signal feedback and no communication capability

7. Schematic Application Circuit Principle

AC Power → Terminal 1 → Internal NO contact of thermostat → Terminal 2 → Cabinet cooling fan → Neutral line

Contacts close when temperature threshold is reached to complete the circuit and drive the fan.

For high load current: Use thermostat contacts to energize an auxiliary relay coil; the relay main contacts drive the fan to protect thermostat contacts from arc erosion.

Temperature Adjustment Operating Guide for Schneider NSYCCOTHO

1. Visual Identification

Equipped with blue adjustment knob, temperature scale range: 0°C ~ 60°C

Terminale: 1, 2 (NO contacts for cooling fan control)

Montare: DIN rail installation inside control cabinet

Important Precondition: This mechanical bimetallic thermostat has fixed inherent hysteresis of 4~6°C, which cannot be eliminated.

Exemplu: Setpoint 40°C for fan startup; fan will shut down approximately between 34~36°C.

2. Standard Adjustment Procedures
3. Safety Precaution

Power off before adjustment where possible. If live commissioning is required, avoid touching live terminals to prevent short circuits.

2. Locate the front adjustment knob

The knob center features a flathead screwdriver slot; temperature markings are printed around the outer dial.

3. Recommended Tool

Small flathead screwdriver. Do not pry the knob forcibly with sharp objects.

4. Adjustment Rules

Clockwise rotation → Higher set temperature

Counter-clockwise rotation → Lower set temperature

5. Calibration Reference

A white indicator line on the knob aligns with the outer scale to define the target activation temperature.

Practical Reference (General Electrical Cabinet Settings)

Standard VFD / PLC cabinet: Align indicator line to 35°C～40°C

Sens: Cabinet temperature ≥ setpoint → Contacts close, fan activates for cooling.

3. Two Commissioning Methods

Metodă 1: Static Preset (Power Off)

Rotate knob directly to target temperature; the thermostat operates per threshold after power-up.

Metodă 2: Live On-site Precision Commissioning

1. Place a thermometer inside the cabinet to measure internal air temperature;
2. Rotate knob slowly and observe fan ON/OFF status;
3. Record fan start temperature (actuation point = dial scale value);
4. Wait for temperature drop and record fan stop temperature (to verify hysteresis).

⚠️ Key Note: The printed value on the dial = fan activation temperature when contacts close, NOT the fan stop temperature!

4. Recommended Setpoints for Common Scenarios

5. Critical Notes & Common Mistakes
6. ❌ Never apply excessive force to turn the knob

Internal thread actuator can strip under heavy force, causing permanent thermostat failure.

2. ❌ Do not mount adjacent to heat-generating components

The thermostat measures cabinet ambient air temperature. Mounting close to inverters, resistors or heat sources leads to distorted temperature readings.

3. ✅ Optimal mounting position: Mid-cabinet within circulating airflow, away from heaters and air outlets.
4. If the fan cycles frequently: Increase set temperature appropriately. Frequent cycling occurs when ambient temperature hovers near the threshold. The only permanent solution is upgrading to an electronic thermostat, as hysteresis cannot be reduced on mechanical models.
5. No locking mechanism required after adjustment. For high-vibration sites, apply a small amount of thread locker (avoid dripping into the rotary shaft gap).
6. Diagnosticarea defecțiunilor (No Response after Adjustment)
7. Rotate fully to minimum scale (0°C): Contacts should close, fan runs continuously;
8. Rotate fully to maximum scale (60°C): Contacts should open at ambient temperature, fan stops;
9. If above tests fail: Internal bimetallic mechanism damaged; thermostat requires replacement.