| ¡¡MZ2 Series for
overcurrent protection in telecom |
 Advanced
developments in telephony equipment in rencent years have
radically altered the protection requirements for both exchange
and subscriber equipment. The PTC thermistor must protect
the telephone line circuit against overcurrent, which may
be caused the following examples:
¡ô Surges due to lighting strikes on or near to the line plant.
¡ô Short-term induction of alternating voltage from adjacent
power lines or
¡¡ railway systems ,usually caused when these lines or systems
develop
¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡¡ faults.
¡ô 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;see Fig.1. However, even with primary line protection
(usually a gas discharge tube ),the PTC thermistor must fulfill
severe requirements.
Surge pulses of up to 2 KV can occur and in order to withstand
short-term power induction the PTC thermistor must withstand
hign voltages. If the line has primary protection, a 220V
to 300V PTC thermistor is adequate. Without primary protection,600V
PTC device is necessary.. Ampron manufactures a range of PTC
thermistor covering both requirements.
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Fig.1
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Fig.2
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Fig.3
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Fig.4
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Component
outline
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Fig.5
Examples of application
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MARKING
OF PARTNUMBER£º
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SPEC.TABLE
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Part
No.
|
Non-trip
Current (mA)
|
Rated
Resistance(¦¸)
|
Responding
Time(sec)
|
3A
¡ý
0.5A |
1A
¡ý
0.5A |
0.5A
¡ý
0.15A |
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MZ21-18RM110A
|
110
|
18¡À20%
|
0.18
|
1.1
|
6.0
|
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MZ21-18RM110B
|
110
|
18¡À20%
|
0.18
|
1.1
|
6.0
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MZ22-12RM100
|
100
|
12¡À20%
|
0.2
|
1.5
|
12.0
|
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MZ22-12RM080
|
80
|
12¡À20%
|
0.2
|
1.2
|
10.0
|
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MZ23-12RM080
|
80
|
12¡À20%
|
0.2
|
1.5
|
12.0
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MZ23-12RM060
|
60
|
50¡À20%
|
0.1
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0.5
|
2.0
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MZ23-50RM050
|
50
|
50¡À20%
|
0.1
|
0.5
|
2.0
|
|
MZ23-55RM060
|
60
|
55¡À20%
|
0.1
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0.65
|
4.0
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Part
No.
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Vmax.(Vrms)
|
Fail
Model
|
Dimensions(mm)
|
| Dmax |
Tmax |
§¶d |
F |
Fig |
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MZ21-18RM110A
|
250
|
¢ñ
|
5.5¡«7.2
|
1.6¡«2.2
|
|
|
1
|
|
MZ21-18RM110B
|
250
|
¢ñ
|
5.5X5.5
|
1.8¡«2.2
|
|
|
2
|
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MZ22-12RM100
|
250
|
¢ñ
|
9.6
|
5.2
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5.2
|
3
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MZ22-12RM080
|
250
|
¢ñ
|
9.6
|
5.2
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5.2
|
3
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MZ23-12RM080
|
250
|
¢ñ
|
8.5
|
5.0
|
0.6
|
5.0
|
4
|
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MZ23-12RM060
|
300
|
¢ñ
|
8.5
|
5.0
|
0.6
|
5.0
|
4
|
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MZ23-50RM050
|
600
|
¢ò
|
8.5
|
5.0
|
0.6
|
5.0
|
4
|
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MZ23-55RM060
|
650
|
¢ó
|
9.0
|
5.0
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0.6
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5.0
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4
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¢ñ.Voltage
of power supply:250Vrms,Initial current:10Arms,Time:30minute.
¢ò.Voltage of power supply:600Vrms,Initial current:15Arms,Time:30minute.
¢ó.Voltage of power supply:650Vrms,Initial current:10Arms,Time:30minute. |
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