MZ9 | GUILCOR SENSORS

MZ9
Temperature sensors

Compact and precise PTC sensor for monitoring and protection in electronic devices and industrial applications.

Maximum precision
+/- 3,0°K

Minimum temperature
-25°C

Maximum temperature
+220°C

Minimum dimensions
2,5 x 9

Response time
Medium

Self-heating
Low

Price
High

Drift
Low

What is a MZ9 sensor ?

The MZ9 is a precision threshold PTC sensor designed to provide enhanced thermal stability and an extended lifespan in demanding industrial environments.

It follows the philosophy of the MZ6/MZ8, but with a sharper switching curve and better retention of characteristics after aging.

Thanks to its advanced ceramic composition and optimized encapsulation, it is ideal for thermal protection of motors, transformers, converters, batteries, and electronic modules.

Operating principle

At its nominal temperature (Tₙ), the sensor exhibits a low resistance (~150 Ω).

When T reaches Tₙ, the resistance increases exponentially, immediately triggering the cutoff signal via the PTC relay.

Temperature (°C)	Typical resistance (Ω)
20	150
100	170
120 (Tₙ)	1650
140	4600
160	11 000
180	22 000
200	40 000

The MZ9 stands out for its threshold reproducibility of ±1 K, even after several hundred thermal cycles.

Technical specifications

Parameter	Typical Value
Nominal temperature (Tₙ)	60 °C to 180 °C according to model
Resistance at 25 °C	150 Ω ±20 %
Resistance to Tₙ	≥ 1650 Ω
Maximum measurement current	2,5 mA
Electrical isolation	≥ 2,5 kV
Response time	3 s
Case	Encapsulated ceramic (high thermal stability)
Standard	DIN 44081 / 44082

Wiring configuration

Type	Description	Precision
2-wire	Series assembly in the detection circuit.	✅ Standard
Multiple chain	Several MZ9s connected in series for multi-zone monitoring.	🏆 Industrial
Integrated	Coated in resin or winding.	💡 Engine applications

Self-heating

At 2.5 mA, the power dissipated is approximately 1 mW → self-heating is less than 0.5 °C, which ensures reliable and fast threshold detection.

Application areas

⚙️ Thermal protection of industrial motors

🔋 Monitoring of high-capacity batteries and DC/DC converters

🧱 Overheating detection in transformers and inductors

🧠 Automatic shutdown systems compliant with DIN 44081/82

🚗 Automotive electronics, protection of IGBT power modules

Should I choose a KTY84-130 sensor ?

Strengths points

🏭 Superior industrial reliability
→ The MZ9 is designed to withstand thousands of thermal cycles, without threshold drift or loss of performance. It is the most stable PTC in the MZ series.
⚙️ Ultra-reproducible triggering
→ The reduced tolerance of ±3 K ensures a precise switching point, ideal for high-end motors and systems with enhanced safety.
🧱 High-strength ceramic housing
→ Resistant to vibrations, thermal shocks, and chemical agents, while maintaining insulation > 2.5 kV. Perfect for harsh environments (batteries, power, railway).

Weaknesses points

🌡️ Binary function only
→ Like all threshold PTCs, it does not allow for continuous temperature measurement, but only for threshold exceedance detection.
💰 Slightly higher cost
→ Its reinforced ceramic design and factory quality control make it the most expensive model in the MZ range.
🔋 Requires a DIN compatible PTC relay
→ The MZ9 cannot operate alone: it must be paired with a detection module to correctly interpret the resistance signal.

Useful information

Here is some useful information regarding the MZ9 sensors.

Tolerances and precision classes

The MZ9 represents the most precise and stable generation of threshold PTCs, designed for critical applications.

Compliant with DIN 44081 / 44082 standards, they stand out for their trigger reproducibility of ±1 K and their exceptional long-term stability.

Type MZ9	Nominal temperature (Tₙ)	Tolerance (Tₙ)	Resistance at 25 °C (R25)	Resistance to Tₙ	Applicable standard
MZ9-60	60 °C	±3 K	150 Ω ±20 %	≥ 1650 Ω	DIN 44081
MZ9-80	80 °C	±3 K	150 Ω ±20 %	≥ 1650 Ω	DIN 44081
MZ9-120	120 °C	±3 K	150 Ω ±20 %	≥ 1650 Ω	DIN 44081
MZ9-150	150 °C	±3 K	150 Ω ±20 %	≥ 1650 Ω	DIN 44082
MZ9-180	180 °C	±3 K	150 Ω ±20 %	≥ 1650 Ω	DIN 44082
MZ9-200	200 °C	±3 K	150 Ω ±20 %	≥ 1650 Ω	DIN 44082

🔹 Remarks:

The MZ9 guarantees stability of the switching point even after 1000 thermal cycles.
The inter-sensor threshold dispersion is reduced to ±1 K — the best on the market.
The high-density ceramic body provides increased mechanical and electrical resistance.

Integration diagram in an electronic system

The MZ9 integrates into the same protection architectures as the MZ8, but it is recommended for high-reliability environments (precision motors, frequency converters, railway systems, etc.).

Component	Function
MZ9 (PTC high precision threshold)	Thermal trigger sensor
Relay or PTC DIN module	Overheat detection (cut-off at 1.5–4 kΩ)
24 V DC Power Supply	Order source
Switch / dimmer	Automatic load disconnection

🔹 Functional diagram (ASCII)

        +24 V
          │
     [PTC Detection Module]
          │
     ├────┴────┐
     │         │
 [MZ9-150]  [MZ9-150]
 (on two engine zones)
     │         │
     └────┬────┘
          │
         GND

🔹 Operating Principle

1️⃣ The relay sends a constant measurement current (< 2.5 mA) in the PTC chain.

2️⃣ As long as T < Tₙ, the total resistance < 750 Ω → relay active.

3️⃣ As soon as a sensor exceeds Tₙ → resistance > 4 kΩ → relay opens → immediate motor shutdown.

🔹 Best Practices

🧩 Use sensors with the same Tₙ and the same series (MZ9) for consistent triggering.
⚡ Do not exceed the specified measurement current (2.5 mA max).
💧 Ensure protection against moisture (resin or insulating varnish).
🧱 Place sensors as close as possible to thermal risk areas (windings, heat sinks).
🔄 Replace all sensors in the chain at the same time during maintenance.

Application example – Simplified equation

The MZ9 operates according to a sharp transition law, comparable to the MZ8 but with a steeper trigger slope and reduced tolerance.

R(T) = { R₀ [1 + α(T - 25)] for T < T_N

{ R_N × e^{β(T - T_N)} for T ≥ T_N

with:

• R₀ = 150 Ω

• α = 3 × 10⁻³ K⁻¹

• R_N = 1650 Ω

• β = 0.27 K⁻¹

🔹 Example 1: normal regime (T = 100 °C, model MZ9-150)

R(100) = 150 × [1 + 3×10⁻³ × (100 - 25)] = 150 × 1.225 = 183.8 Ω

✅ Result: normal operation, temperature below threshold, no alarm.

🔹 Example 2: overheating (T = 170 °C)

R(170) = 1650 × e^(0.27 × (170 - 150)) = 1650 × e^5.4 ≈ 1650 × 222.5 = 367,125 Ω

✅ Result: the resistance reaches ≈ 370 kΩ, a clear signal of overheating — relay triggered.

🔹 Practical notes

The MZ9 offers a sharper switching action than the MZ6/MZ8, reducing the risk of ambiguity.
Ideal for critical systems requiring a fast and repeatable thermal response.
The measurement current must remain below 2.5 mA to preserve the threshold behavior.