Ceramic PTC Thermistor for High Voltage Current Surge Protection
Ceramic positive temperature coefficient PTC thermistors help provide protection against power cross, power induction surges and lighting surge defined in ITU, Telcordia, UL. Available in chip, radial-leaded coated and non-coated configuration. This thermally sensitive semiconductor resistor provides reversible, self-resetting fuse protection against over-currents short circuit for telecommunication line protector units, improve the reliability of custom premises and network equipment.
PTC Thermistors Current Limiting Protection Device can be found providing resettable line protection at the exchange, monitoring hot spots and protecting ringers, battery feeds, transformers, switches and relay circuits. Also used extensively to protect the mobile phone's battery pack against overcharging in land-based and radio mobile communications.
Advanced developments in telecom equipment in recent years have radically altered the protection requirements of both exchange and subscriber equipment. PTC Thermistor Current Protector must protect the telephone line circuit against overcurrent, which may be caused by the following examples:
Surges due to lighting strikes on or near to the line plant.
Short-term induction of alternating voltage from adjacent power lines or railway systems, usually caused when these lines or systems develop faults
Direct contact between telephone lines and power lines.
To provide good protection under such conditions, a PTC thermistor is connected in series with each line, usually as secondary protection; However, even with primary line protection (usually a gas discharge tube), the PTC thermistor must fulfill severe requirements.
Surge pulses of upto 2KV can occur and in order to withstand short term power induction, the PTC thermistor must withstand high voltages. If the line has primary protection, a 220V to 300V PTC thermistor is adequate. Without primary protection, 600V PTC device is necessary. We can manufacture a series of PTC thermistor fulfilling both requirements.
High Voltage Current Surge Protection PTC Thermistor Application in Telecommunication Equipment
Central Office Switching Equipment (C.O): analog and digital line cards, POTS, T1/E1 equipment, xDSL modems and splitters, multiplexers, CSU/DSU, servers.
Primary Protection Modules: MDF (main distribution frame) modules, network interface devices (NIC).
Custom Premises Equipment, also known as subscriber terminal equipment (T.E.), IT equipment: Modem, phone sets, fax machines, phone wall outlet (plugs), alarm systems, answering machine, PBX systems, ADSL Splitters, internet appliance, POS terminals.
Access Network hardware, LAN WAN equipment, Powered Ethernet systems, VoIP (voice over IP equipment), integrated voice data (IVD), Set-top box (S.B), etc.
PTC Thermistor Current Protector Features
Compliant with ITU-T K20 K21 K45
--Basic level lightning surges (10/700¦Ìs)
--Basic level power Induction (600V,1A,0.2S)
--Power contact criteria A/B (230V,15min.)
Suitable for continuous connection to main voltage 110/230 VAC in tripped (high ohmic) condition.
Round leadless disk thermistor available for combined usage of PTC and primary protection, e.g gas arrestor.
Thermistor disk coated non-coated construction, diameter 5mm to 10mm.
Typical Resistance @25C (R25) 10 ohm, 12 ohm, 18 ohm, 20 ohm, 25 ohm, 50 ohm, 55 ohm.
Matching available with narrow resistance tolerance.
Tight resistance tolerance maintained after switching.
Negligible resistance drift after soldering or switching.
PTC Thermistors Overload Surge Current Protection Electrical Performances
Rated zero-power Resistance(R25)
Operating temperature range: 25¡À2¡æ, Within the allowable tolerance.
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Non-operating characteristic
Operating temperature range: 40¡À2¡æ. In static air for 30min.Max. voltage: 60VDC. Non-operating current. Energized time: 60min. (R-R25)/R25¡Ü50%
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Over-current operating characteristic
Operating temperature range: 25¡À2¡æ,Max. voltage of power supply: 220Vrms.Test the time for the current decrease to limited value. See the spec. Table.
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Over voltage withstanding (Power line contact)
Voltage of power supply: 250VAC, Initial current: 3A,Energized time: 30min . Restore time in room temperature is 4 hours, then test the R25. ¦¤R/R25¡Ü20%.
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Over current withstanding
Max. voltage of supply: 220VAC, Initial current: 3A. ON 60S, OFF 600S,Cycle:30 times, Restore time in room temperature is 4 hours, then re-test the Rn.
¦¤R/Rn¡Ü20%.
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Surge current withstanding
Current waves: 10/1000¦ÌS, Minimum opening circuit voltage: 1.0kv, Peak current: 25A, Interval: 3min, Cycle:30 times, Restore time in room temperature is 4 hours, then re-test the R25. ¦¤R/R25¡Ü20%.
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Induction voltage current withstanding (Only for maximum voltage more than 600V)
Max. voltage of supply: 650VAC, Initial current: 1.1A.,ON 60S, OFF 600S,Cycle:10 times, Restore time in room temperature is 4 hours, then re-test the R25. ¦¤R/R25¡Ü20%.
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Fail Model
I. Voltage of power supply: 250VAC. Initial current: 10Arms,
II. Voltage of power supply: 600VAC. Initial current: 15Arms.
III. Voltage of power supply: 650VAC. Initial current: 10Arms.
Energized time: 30min. High resistance or open circuit is allowable. Low resistance state or firing is not allowed..
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Restore time
The necessary time of a PTC to return to twice of R25. ¡Ü60S.
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PTC Thermistor Current Protector Outline and Dimensions (unit:mm)
Fig.5 Twin Surface Mount PTC Thermistor for Telecom Protection AMZ26 Outlook and Dimension
PTC Thermistor for Telecom Line Card Protection Application
Part number |
Resistance @25C
R25
£¨Ohm£© |
Non-trip current
Int£¨mA£© |
Trip current
@25C
It
£¨mA£© |
Tripping time at max current
(Seconds) |
Max. current
Imax
(A) |
Max. voltage
Vmax
(V) |
Fail model |
Dimension £¨mm£© |
@25C |
@40C |
Dmax |
Tmax |
¦µd |
AMZ23-10RM130 |
10 ohm |
130mA |
100mA |
260mA |
<0.2s |
2.0A |
250V |
250V/10A |
7.5 |
4.0 |
0.6 |
AMZ23-10RM150 |
10 ohm |
150mA |
100mA |
260mA |
<0.3s |
2.0A |
250V |
250V/10A |
9.0 |
5.0 |
0.6 |
AMZ23-12RM130 |
12 ohm |
130mA |
100mA |
260mA |
<0.3s |
2.0A |
250V |
250V/10A |
9.0 |
5.0 |
0.6 |
AMZ23-12RM090 |
12 ohm |
90mA |
60mA |
160mA |
<0.2s |
2.0A |
250V |
250V/10A |
9.0 |
5.0 |
0.6 |
AMZ23-20RM100 |
20 ohm |
100mA |
80mA |
200mA |
<0.2s |
3.0A |
250V |
250V/10A |
9.0 |
4.0 |
0.6 |
AMZ23-35RM090 |
35 ohm |
90mA |
75mA |
180mA |
<0.2s |
3.0A |
250V |
250V/5A |
9.0 |
5.0 |
0.6 |
AMZ23-40RM080 |
40 ohm |
80mA |
70mA |
160mA |
<0.2s |
3.0A |
250V |
250V/5A |
9.0 |
5.0 |
0.6 |
AMZ23-50RM070 |
50 ohm |
70mA |
60mA |
150mA |
<0.2s |
3.0A |
250V |
250V/5A |
9.5 |
5.0 |
0.6 |
AMZ23-50RM075 |
50 ohm |
75mA |
60mA |
150mA |
<0.2s |
3.0A |
650V |
650V/10A |
9.5 |
5.0 |
0.6 |
AMZ23-55RM070 |
55 ohm |
70mA |
60mA |
150mA |
<0.2s |
3.0A |
650V |
650V/10A |
9.5 |
5.0 |
0.6 |
AMZ25-9RM160 |
9 ohm |
160mA |
130mA |
330mA |
<0.8s |
3.0A |
250V |
250V/10A |
10.5 |
4.5 |
0.6 |
AMZ25-25RM100 |
25 ohm |
100mA |
80mA |
220mA |
<0.2s |
3.0A |
250V |
250V/10A |
6.6 |
4.0 |
0.6 |
AMZ25-25RM120 |
25 ohm |
120mA |
100mA |
300mA |
<0.4s |
3.0A |
250V |
250V/10A |
8.2 |
4.0 |
0.6 |
AMZ26-35RM080SMD |
35 ohm |
80mA |
60mA |
180mA |
<0.2s |
2.5A |
250V |
250V/10A |
/ |
/ |
/ |
Note: Standard Resistance @25C (R25) allowable tolerance +/-20%, if not specified.
PTC Thermistor for Telecom MDF (Main Distribution Frame) Protection Application
Part number |
Resistance @25C
R25
£¨Ohm£© |
Non-trip current
Int
£¨mA£© |
Trip current @25C
It
£¨mA£© |
Tripping time at max current
(Seconds) |
Max. current
Imax
(A) |
Max. voltage
Vmax
(V) |
Dimension £¨mm£© |
@25C |
@40C |
Dmax |
Tmax |
¦µd |
AMZ21-10RM150 |
10 ohm |
150mA |
130mA |
350mA |
<4.0s |
3A |
230V |
7.2 |
1.5 |
/ |
AMZ21-18RM110 |
18 ohm |
110mA |
90mA |
220mA |
<0.15s |
3A |
250V |
5.5 |
1.5 |
/ |
AMZ21-18RM125 |
18 ohm |
125mA |
110mA |
250mA |
<0.18s |
3A |
250V |
5.5 |
2.0 |
/ |
AMZ21-18RM130 |
18 ohm |
130mA |
110mA |
260mA |
<0.18s |
3A |
250V |
6.2 |
2.0 |
/ |
AMZ21-18RM135 |
18 ohm |
135mA |
110mA |
270mA |
<0.2s |
3A |
250V |
6.6 |
2.0 |
/ |
AMZ21-20RM085 |
20 ohm |
85mA |
70mA |
170mA |
<0.18s |
3A |
250V |
6.2 |
2.0 |
/ |
AMZ21-25RM055 |
25 ohm |
55mA |
45mA |
110mA |
<0.4s |
2A |
230V |
5.3 |
2.0 |
/ |
AMZ21-25RM060 |
25 ohm |
60mA |
50mA |
120mA |
<0.4s |
2A |
230V |
5.3 |
2.0 |
/ |
AMZ21-25RM085 |
25 ohm |
85mA |
75mA |
170mA |
<0.7s |
2A |
230V |
5.3 |
2.0 |
/ |
AMZ25-25RM055 |
25 ohm |
55mA |
45mA |
110mA |
<0.4s |
1A |
230V |
5.3 |
4.0 |
0.6 |
AMZ25-25RM060 |
25 ohm |
60mA |
50mA |
120mA |
<0.4s |
1A |
230V |
5.3 |
4.0 |
0.6 |
AMZ25-20RM145 |
20 ohm |
145mA |
100mA |
250mA |
<0.2s |
3A |
250V |
6.6 |
4.0 |
0.6 |
AMZ25-10RM130 |
10 ohm |
130mA |
110mA |
260mA |
<4.0s |
1A |
230V |
6.6 |
4.0 |
0.6 |
AMZ25-10RM150 |
10 ohm |
150mA |
135mA |
300mA |
<7.0s |
1A |
230V |
8.2 |
4.0 |
0.6 |
AMZ25-18RM125 |
18 ohm |
125mA |
110mA |
250mA |
<1.0s |
1A |
230V |
5.5 |
4.0 |
0.6 |
AMZ23-18RM135 |
18 ohm |
135mA |
110mA |
270mA |
<0.2s |
3A |
250V |
7.5 |
4.5 |
0.6 |
AMZ23-18RM110 |
18 ohm |
110mA |
90mA |
220mA |
<0.2s |
3A |
250V |
9.0 |
4.5 |
0.6 |
AMZ23-20RM100 |
20 ohm |
100mA |
80mA |
200mA |
<0.2s |
3A |
250V |
9.0 |
4.5 |
0.6 |
AMZ23-25RM085 |
25 ohm |
85mA |
75mA |
170mA |
<0.7s |
1A |
230V |
6.5 |
5.0 |
0.6 |
AMZ23-25RM090 |
25 ohm |
90mA |
70mA |
180mA |
<0.2s |
3A |
250V |
9.0 |
4.5 |
0.6 |
Note: Standard Resistance @25C (R25) allowable tolerance +/-20%, if not specified.

Typical telephone line showing where PTC thermistors can be used for overcurrent protection
An example of PTC Thermistors for telecom circuit protection
Keep Reading: ‘Power NTC Thermistors for Inrush Current Limiting Surge Supression’ »
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