PSTT PC / PSTT SC / PSTT ZC
Active Trigger Units for Thyristors
The Active Trigger is an economic replacement of
pulse transformers including all associated circuitry in
phase controlled thyristor equipment. Due to the small
control current it becomes the ideal link between any
size of thyristor and the control intelligence. Each
Active Trigger can trigger two thyristors and is
intended for mains voltages from 115V to 690Vrms.
Its operation is based on an optically activated current
source connected between anode and gate of the
thyristor to be triggered. Thus a small electrically
isolated control current initiates a large gate current
without the necessity of a gate drive power supply.
Three different application specific types are
available.
PSTT PC
- controlled rectifiers, ac controllers, dc motor control, all other applications
PSTT SC
- economic low cost ac controllers
PSTT ZC
- zero crossing switching – heating, welding, power factor correction
PSTT PC
Top view in mm
PSTT SC
A2
G2
K2
Top view in mm
K2
G2
PSTT ZC
G1
K1
G1
K1
Height 23 mm
PCB hole size 0.8 mm
Height 19 mm
PCB hole size 0.8 mm
ABSOLUTE MAXIMUM RATINGS
Type
PSTT PC/12
PSTT PC/20
PSTT SC/12
PSTT SC/20
PSTT ZC/12
PSTT ZC/20
Vp
1200
2000
Peak voltage-positive and negative
Nominal mains voltage
Vm
400
690
Continuous DC voltage
V=
400
690
Turn-on delay for gate current >1A
tgd
5
5
Input-output isolation
Vi
5300Vrms 60Hz 1min VDE0884
Input-output transient immunity
(dv/dt)c
5000
Device transient immunity
(dv/dt)d
2000
Ambient temperature range
Ta
-25 to +85
External gate cathode short circuit during operation can be destructive
Parameter
Symbol
Unit
V
Vrms
Vdc
µs
V/µs
V/µs
°C
POWERSEM GmbH, Walpersdorfer Str. 53
2006 POWERSEM reserves the right to change limits, test conditions and dimensions
91126 D- Schwabach
1/3
Phone: 09122 - 9764-0 Fax.: 09122 - 9764-20
PSTT PC / PSTT SC / PSTT ZC
TECHNICAL DATA
at 25°C
Type
Parameter
200mA gate current threshold
1.2A gate current threshold
Gate current rise time at anode
Voltage of
PSTT PC/12
PSTT SC/12
PSTT ZC/12
10
24
2.5
3
4
6
1.3
4.4
2*
7
12
typ. 1.2<1.5
6
25
<20
PSTT PC/20
PSTT SC/20
PSTT ZC/20
16
36
1.2
2
2.5
3
4
1.3
5.1
2*
7
12
typ. 1.2<1.5
6
25
<20
Symbol
Vgtl
Vgth
100V
200V
400V
800V
1200V
(di/dt)g
Unit
V
V
A/µs
A/µs
A/µs
A/µs
A/µs
A
mA
µA
mA
mA
V
V
µs
V
Peak gate current (typical)
Anode-cathode current at Vp
Maximum off state gate current
Minimum control current
Recommended control current
Control input voltage drop at 12mA
Maximum reverse control input voltage
Turn-on delay time at Ic=12mA
Zero crossing threshold for PSTT ZC
Ip
In
Io
Icm
Ic
Vin
Vinr
tdi
Vzt
*PSTT ZC < 40µA
HIGHLIGHTS
Economic – very easy to use – small size – powerful gate pulse triggers large and small
thyristors. Eliminates gate drive power supply – proven reliability in harsh industrial
environment.
APPLICATION INFORMATIONS
As the gate current is derived from the anode of the thyristor, the control circuit only
needs to supply the recommended control current which can be supplied directly from
the output of many logic devices. It is advisable to maintain the control current over the
entire conduction period of the thyristor. Once the thyristor is triggered, the gate current
ceases to flow because the anode voltage drops below the threshold voltage.
The control input consists of the light emitting diode of an optocoupler. Any such optical
component is subject to aging at elevated temperatures. Although the minimum control
current Icm is well below 7mA, a 12mA control signal is recommended to ensure reliable
operation beyond 100’000 hours in a worst case design. The turn-on delay tdi can be
reduced by pulse shaping, because it is inversely proportional to the control current.
Because the device derives its power from the anode of the thyristor, a minimum
operating voltage is required before any current can flow from the anode to the gate.
This threshold voltage limits the minimum regulated output voltage. For example for a
single-phase 115V ac controller triggered by a 1200V unit it is below 0.12%. For a 400V
supply it is much less and can safely be neglected in most applications.
POWERSEM GmbH, Walpersdorfer Str. 53
2006 POWERSEM reserves the right to change limits, test conditions and dimensions
91126 D- Schwabach
2/3
Phone: 09122 - 9764-0 Fax.: 09122 - 9764-20
PSTT PC / PSTT SC / PSTT ZC
The thyristor is triggered from a current source with a maximum voltage of 22V. This
allows for twisted gate leads of up to 1m while maintaining a high rate of rise of the gate
current.
Note that the envelope of the voltage across the thyristor to be triggered can have any
desired shape provided the rms value is below Vm and the peak value does not exceed
Vp.
Both the PSTT SC and PSTT ZC have one control input only. This means that the
thyristor with a positive anode voltage will be triggered when a control signal is present.
The connection diagrams below show the typical application of the Active Trigger in
mains operated systems using thyristors with current ratings from a few Amps up to
several thousand Amps.
CONNECTING DIAGRAMS
PSTT PC
A2
+Vs
Logic
Output
PSTT SC
PSTT ZC
K1
G1
+
-
+
+Vs
G2
K2
12mA
sink
G2
-
12mA
sink
Logic
Output
+
G1
K1
-
K2
POWERSEM GmbH, Walpersdorfer Str. 53
2006 POWERSEM reserves the right to change limits, test conditions and dimensions
91126 D- Schwabach
3/3
Phone: 09122 - 9764-0 Fax.: 09122 - 9764-20
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