Download LBDS_Trigger_Delay

TRIGGER DELAY
100µs
Requirements
• The trigger delay is a back-up system that generates an
asynchronous dump trigger for MKD and MKB in case of
problems with the synchronous dump trigger.
• Design goals are to make a system that is stand-alone,
simple and reliable.
• Stand–alone means that the system is completely selfcontained. Its function is not affected by any external
condition.
• Simplicity means to minimise number of components for
the critical part of the circuit.
G. Gräwer AB/BT/EC
LBDS Trigger Delay
2
Block diagram
230VAC
3U Eurochassis
Trigger
In
VB
Power
supply B
24VDC
VA
Power
supply A
24VDC
Delay 100µs
Interlock
loop
To 25 retrigger boxes
15 MKD and 10 MKB
Error
Warning
Interlock
Trigger
Out
To PLC
G. Gräwer AB/BT/EC
LBDS Trigger Delay
3
General description
• The trigger delay generates an output pulse 100µs after the
input trigger
• The trigger delay unit has got two internal 24V power
supplies. If one of them fails it continues working with the
other one and a warning signal is generated for the PLC. The
faulty power supply should be replaced at the next possible
occasion.
• If both power supplies fail or in case of mains failure supply
voltage is maintained by internal capacitors. The unit still
remains operational for several minutes (up to 30min).
• In case of a fault in the trigger delay unit the interlock circuit
generates an error signal for the PLC.
• There are three possible faults that can cause an error:
• Input disconnected.
• Output disconnected.
• Low voltage of oscillator capacitor.
G. Gräwer AB/BT/EC
LBDS Trigger Delay
4
G. Gräwer AB/BT/EC
VCAP
LBDS Trigger Delay
BZX55C12
220n
C5
47
T1
R6
D24
D7
D4
BZX55C15 BZX55C15
D25
1k, 1W
R5
2µ2, 35V
1k2, 1W
ZKB T60403D4097-X054
1N4151
D16
22n
100
D9
100k
C8
R4
1N5060
1k
C16
VB
R16
47n
R43
1N5060
R17
1N4151
Trigger in
100
D15
VT
R15
D3
10µ
C3
1N4151
100, 1W
350µ
L1
D5
R1
710n
C7
15
27k
1N4151
BYV27-200
C6
R9
D2
2N2324
1N4151
D14
Q1
R13
470
220
32Z
R14
1N4151
68
R12
D1
VT
D11
VB
1N4151
D12
R11
VA
1N4151 1N4151 1N4151
D13
D10
24V in
30Z
YELLOW
D8
Trigger
Schematic of trigger delay
VA
C1
10m, 40V
1:1:1
Trigger
out
4Z
6Z
8Z
M1
IRFF130
5
Principle of operation
Main circuit
• The trigger delay circuit is completely analogue. The
semiconductors used in the critical part of the circuit are one
thyristor Q1, one MOSFET M1 and several diodes. The delay
time is determined by one period of an LC oscillator L1 and
C7.
• A trigger pulse at the input triggers Q1. For the first half of the
oscillation the current flows through Q1 until the zero
crossing. For the second half of the oscillation the current
changes direction and flows through the diode D14 while Q1
is turned off. At the end of the oscillation Q1 blocks the
voltage VT. The rising edge of VT turn on M1 and this
generates the output trigger pulse.
G. Gräwer AB/BT/EC
LBDS Trigger Delay
6
Principle of operation
Interlock circuit
• The Interlock circuit monitors the internal 24V supply
voltages, the voltage VT at Q1 and the interlock loop.
• If one of the supply voltages fails a warning signal is
generated.
• If VT stays low for too long, the interlock loop is broken or the
input is disconnected an error signal is generated. The cable
from the trigger delay unit to the retrigger boxes contains two
pairs of wires. One for the trigger signal and one for the
interlock loop. At the end of the cable the interlock loop must
be shorted. This is to make sure that the trigger cable is
properly connected.
G. Gräwer AB/BT/EC
LBDS Trigger Delay
7
Waveforms
Oscillator
current
Oscillator
Voltage
Trigger in
Trigger out
VT
G. Gräwer AB/BT/EC
LBDS Trigger Delay
8
Input fault detection
Trigger line with fault detection
+12V
C1
C2
50W coaxial cable
OUT
IN
220k
2k
R4
Trigger pulse on
cable with
offset voltage
R3
47n
R2
47n
OUT
50
IN
Trigger
Receiver
2k
R1
Trigger
Driver
Voffset
C3
1n
IN
Trigger pulse at
driver output.
Rise time <100ns
OUT
Schmitt trigger monitors
offset voltage.
Error if offset voltage
below threshold.
Time constant
R4, C3 >>time
constant trigger
pulse
The voltage divider R1, R2 generates an offset voltage that is monitored by the schmitt trigger on
the receiver side. If the driver is not working or the cable is broken the offset voltage is low or zero
and an error signal is generated.
G. Gräwer AB/BT/EC
LBDS Trigger Delay
9
VT
VC
R20
20M
2M2
R21
R19
220k
VD
2k2
R18
Trigger
Schematic of interlock circuit
CD4093B
2
IC1:A
Interlock
loop
VD
&
IC1:B
5
6
CD4093B
2n2
R22
11M
C10
1n
C9
3
&
1
R23
14Z
1k, 1W
16Z
1N5060
D18
2µ
1M
C12
1k, 1W
VD
D17
R25
VB
R24
4
VA
VD
VD
8
R33
11
&
9
&
Q8
R36
2N2219A
16
4
K2
1N4151
8
D23
6
RED
1
D22
1N4151
K1
R42 680
R40
10k
D21
GREEN 1k5, 1W
R41 680
10k
GREEN 1k5, 1W
220n
RED
D20
R39
110k
C15
1k2, 1W
IC1:C
2N2219A
110k
R38
BZX55C12
VD
4k7
Q7
R35
220n
R37
R30
R34
10
VD
4k7
IC1:D
C14
2k2
Q5
BC107B
CD4093B
12
VC
D19
R32
Q6
2N2905A
Q3
BC107B
CD4093B
13
VC
22k
2k2
R29
VC
Q4
2N2905A
22k
R31
R28
200k
200k
R27
R26
VC
10n
C13
1N5060
1
16
6
8
4
24Z
26Z
14
100n
C11
28Z
IC1
18Z
20Z
7
22Z
G. Gräwer AB/BT/EC
Error
LBDS Trigger Delay
Warning
10
Trigger delay PCB
G. Gräwer AB/BT/EC
LBDS Trigger Delay
11