Coil Temperature Sensor

Applications

Motors, generators, and transformers to prevent overheating

Industrial machinery with high-current windings

HVAC systems, compressors, and pumps for motor protection

Battery packs or electric vehicles where motor windings require thermal monitoring

Features

High Accuracy & Reliability

Fast Thermal Response : Small bead or thin-film designs allow rapid detection of temperature changes.

Overheat Protection Compatible: Can be integrated with relay or microcontroller-based protective circuits to prevent insulation failure.

High Stability & Long Life : Resistant to thermal cycling, vibration, and electrical stress typical in motor windings.

Options

(Available on request)

Operating Temperature : –40°C to +125°C / up to +150°C for glass type

Sensor Type : Bead / Disc / Epoxy coated / Glass encapsulated / Probe type

Encapsulation : Epoxy, glass, or resin-coated bead; insulated for embedding in coils

Leads : Flexible insulated wires (PTFE, silicone) or tinned copper leads

Mounting Options: Embedded in windings, attached to coil surface, or probe style for insertion

Rated Temperatures and Dissipation Factor

Lower Temperature : -40°C

Upper Temperature : 140°C

Max Permissible Power at 25°C : 60 mW

Resistance Tolerance (ΔR/RN ) : ±0.5%, ±1%, ±2%, ±5%

Rated Temperature (TN) : 25°C

Dissipation factor in air(δth) : approx 1.5 mW/K

Thermal cooling time constant in air (τc) : ≈ 12s

Beta Tolerance (Δβ/βN) : ±1%, ±2%, ±3%,

Heat capacity (Cth) : ≈ 18 mJ/K

Electrical Data (Resistance and Beta Values)

Resistance At 25°C (Ω)		Beta Value (25/85) (K)
2000		3540
2057		3540
2800		3900
3000		3977
4700		3977
5000		3977
10000		3977

Resistance At 25°C (Ω)	Beta Value (25/85) (K)
20000	4000
30000	4050
47000	4100
49300	3960
50000	4100
100000	4400
170000	4250

Reliability Data

Test

Standard

Test Conditions

Change In R

Remarks

Storage in
dry heat

IEC 60068-2- 2

Storage at upper
category temp
T: 100°C t: 1000 h

<2%

No Visible Damage

Storage in
damp heat,
steady state

IEC
60068 – 2- 78

Temp of air:40 °C
Relative humidity
of air: 93 %
Duration: 56 days

<2%

No Visible Damage

Rapid
temperature
cycling

IEC
60068 – 2- 14

Lower test temp:– -30°C
Upper test temp: 150°C
Time to change from
lower to upper
temperature: <30 s
Number of cycles: 1000
Medium: air

<2%

No Visible Damage

Storage in
coldness

Storage at lower
category temp T: -30 °C
t: 1000 h

<2%

No Visible Damage

Vibration
resistance

IEC 60068-2-6

Frequency range: 5 to
500 Hz
Amplitude: 7.5 mm, 2 g
Duration: 3 x 8 h

<3%

No Visible Damage

Long-term
stability
(empirical value)

Temperature: 200 °C
t: 10000 h

<3%

No Visible Damage

Voltage proof Test

1250 V AC, 1 s

<3%

No flashover

Insulation test

The sensors are placed in a
vessel containing metallic
balls of 1 mm diameter (with
total immersed head). The
applied voltage is 100 V DC.

Above
1000 MΩ

STTS	174	R5	E01	K	H	101	4250
	174 – 170K	R2 – 2%	E01- Blue Epoxy Powder Coating	K- PTFE Multi strand copper wire	H- AWG 26	100MM	B(25/85)
			E03 – Epoxy Dip Coating	AA- FEP Multi strand copper wire	F- Awg 28	500MM
		R3 – 3%	E02- Black Epoxy Powder Coating		K – AWG 24	450MM
		R5 – 5%			M – AWG 22

Ordering Codes for NTC Thermistor Sensor For Coil Winding Protection

STLT *** R# E%% @@ $$$ &&&&
*** = Resistance Value at 25°C (e.g. 102- 1000Ω, 201 – 200Ω, 103 – 10kΩ)
# = Resistance Tolerance (eg. R1 – ± 1%, R5 – ±5%)
%% = Encapsulation (eg. E01 – Epoxy Powder Coated (Blue))
@@ = Type of Lead (eg. GC, G – Single strand Nickel Wire(Silver Plated) & C – 30 AWG)
$$$ = Total Length in mm (eg: 250 – 25mm Length, 401 – 400 mm Length)
&&&& = Beta Value (eg:3977K, 3830K)

Coil Temperature Sensor