# Help with Microsim Pspice

A

#### anand

Jan 1, 1970
0
Hi,

I am currently learning the Microsim PSpice Evaluation version 8.In the
transient analysis of circuits,I am unable to remove the initial
conditions in the .tran statement.I get the same result in the probe
analysis for the circuit even when the "UIC" or "SKIPBP" commands are
not included in the .tran statement.I am not sure if I am missing some
other fundamental part in the program which leads to this problem.I
would be grateful if someone could help me out.

Thanks,
Anand

J

#### Jim Thompson

Jan 1, 1970
0
Hi,

I am currently learning the Microsim PSpice Evaluation version 8.In the
transient analysis of circuits,I am unable to remove the initial
conditions in the .tran statement.I get the same result in the probe
analysis for the circuit even when the "UIC" or "SKIPBP" commands are
not included in the .tran statement.I am not sure if I am missing some
other fundamental part in the program which leads to this problem.I
would be grateful if someone could help me out.

Thanks,
Anand

You don't provide enough information. Netlist at minimum... schematic
(on ABSE) preferred.

...Jim Thompson

A

#### anand

Jan 1, 1970
0
Hi,

Thanks for your reply.This is the program I picked up from a PSpice
basics tutorial book.It is a basic RL circuit with a current pulse
source.I have defined the initial conditions for the current in the
inductor in both cases.In the first part of the program,I do not
consider the initial conditions on the inductor and in the second
part,I make use of the initial conditions on the inductor.The problem I
have is the graph I plot using probe gives me the same result for both
cases.The initial current in the inductor for both cases starts from
2.5,when in the first case,it should start from zero.

R-L circuit with pulse source and no IC
Is 0 1 PWL 2,0 2.01,4 5,4 5.01,0
R10 1 0 5
R12 1 2 5
L20 2 0 20 IC=2.5
..tran 15 15
..probe
..end
R-L circuit with pulse source and IC
Is 0 1 PWL 2,0 2.01,4 5,4 5.01,0
R10 1 0 5
R12 1 2 5
L20 2 0 20 IC=2.5
..tran 15 15 UIC
..probe
..end

I do not know if I have misunderstood the concept of the UIC command as
the book does not explain the command or the program in detail.I even
tried substituting the "SKIPBP" command instead of "UIC" and still got
the same result.I would be grateful if you could help me out.

Thank you,
Anand

J

#### Jim Thompson

Jan 1, 1970
0
Hi,

Thanks for your reply.This is the program I picked up from a PSpice
basics tutorial book.It is a basic RL circuit with a current pulse
source.I have defined the initial conditions for the current in the
inductor in both cases.In the first part of the program,I do not
consider the initial conditions on the inductor and in the second
part,I make use of the initial conditions on the inductor.The problem I
have is the graph I plot using probe gives me the same result for both
cases.The initial current in the inductor for both cases starts from
2.5,when in the first case,it should start from zero.

R-L circuit with pulse source and no IC
Is 0 1 PWL 2,0 2.01,4 5,4 5.01,0
R10 1 0 5
R12 1 2 5
L20 2 0 20 IC=2.5
.tran 15 15
.probe
.end
R-L circuit with pulse source and IC
Is 0 1 PWL 2,0 2.01,4 5,4 5.01,0
R10 1 0 5
R12 1 2 5
L20 2 0 20 IC=2.5
.tran 15 15 UIC
.probe
.end

I do not know if I have misunderstood the concept of the UIC command as
the book does not explain the command or the program in detail.I even
tried substituting the "SKIPBP" command instead of "UIC" and still got
the same result.I would be grateful if you could help me out.

Thank you,
Anand
[snip]

L20 has an "IC", irrespective of your UIC command.

Also, lose the commas as delimiters, they can confuse some netlisters.

...Jim Thompson

G

#### Genome

Jan 1, 1970
0
Jim Thompson said:
Hi,

Thanks for your reply.This is the program I picked up from a PSpice
basics tutorial book.It is a basic RL circuit with a current pulse
source.I have defined the initial conditions for the current in the
inductor in both cases.In the first part of the program,I do not
consider the initial conditions on the inductor and in the second
part,I make use of the initial conditions on the inductor.The problem I
have is the graph I plot using probe gives me the same result for both
cases.The initial current in the inductor for both cases starts from
2.5,when in the first case,it should start from zero.

R-L circuit with pulse source and no IC
Is 0 1 PWL 2,0 2.01,4 5,4 5.01,0
R10 1 0 5
R12 1 2 5
L20 2 0 20 IC=2.5
.tran 15 15
.probe
.end
R-L circuit with pulse source and IC
Is 0 1 PWL 2,0 2.01,4 5,4 5.01,0
R10 1 0 5
R12 1 2 5
L20 2 0 20 IC=2.5
.tran 15 15 UIC
.probe
.end

I do not know if I have misunderstood the concept of the UIC command as
the book does not explain the command or the program in detail.I even
tried substituting the "SKIPBP" command instead of "UIC" and still got
the same result.I would be grateful if you could help me out.

Thank you,
Anand
[snip]

L20 has an "IC", irrespective of your UIC command.

Also, lose the commas as delimiters, they can confuse some netlisters.

...Jim Thompson

Seems strange.... The implication is that UIC (Use Initial Conditions)
should be substituted with IIC (Ignore Initial Conditions).....

DNA

J

#### Jim Thompson

Jan 1, 1970
0
Jim Thompson said:
Hi,

Thanks for your reply.This is the program I picked up from a PSpice
basics tutorial book.It is a basic RL circuit with a current pulse
source.I have defined the initial conditions for the current in the
inductor in both cases.In the first part of the program,I do not
consider the initial conditions on the inductor and in the second
part,I make use of the initial conditions on the inductor.The problem I
have is the graph I plot using probe gives me the same result for both
cases.The initial current in the inductor for both cases starts from
2.5,when in the first case,it should start from zero.

R-L circuit with pulse source and no IC
Is 0 1 PWL 2,0 2.01,4 5,4 5.01,0
R10 1 0 5
R12 1 2 5
L20 2 0 20 IC=2.5
.tran 15 15
.probe
.end
R-L circuit with pulse source and IC
Is 0 1 PWL 2,0 2.01,4 5,4 5.01,0
R10 1 0 5
R12 1 2 5
L20 2 0 20 IC=2.5
.tran 15 15 UIC
.probe
.end

I do not know if I have misunderstood the concept of the UIC command as
the book does not explain the command or the program in detail.I even
tried substituting the "SKIPBP" command instead of "UIC" and still got
the same result.I would be grateful if you could help me out.

Thank you,
Anand
[snip]

L20 has an "IC", irrespective of your UIC command.

Also, lose the commas as delimiters, they can confuse some netlisters.

...Jim Thompson

Seems strange.... The implication is that UIC (Use Initial Conditions)
should be substituted with IIC (Ignore Initial Conditions).....

DNA

There IS some discrepancy in the notation...

IC conditions on components seem always to be used.

...Jim Thompson

A

#### anand

Jan 1, 1970
0
Hi,

Thanks.I will remove the "IC" command for the first case.

Anand

Jim said:
Jim Thompson said:
Hi,

Thanks for your reply.This is the program I picked up from a PSpice
basics tutorial book.It is a basic RL circuit with a current pulse
source.I have defined the initial conditions for the current in the
inductor in both cases.In the first part of the program,I do not
consider the initial conditions on the inductor and in the second
part,I make use of the initial conditions on the inductor.The problem I
have is the graph I plot using probe gives me the same result for both
cases.The initial current in the inductor for both cases starts from
2.5,when in the first case,it should start from zero.

R-L circuit with pulse source and no IC
Is 0 1 PWL 2,0 2.01,4 5,4 5.01,0
R10 1 0 5
R12 1 2 5
L20 2 0 20 IC=2.5
.tran 15 15
.probe
.end
R-L circuit with pulse source and IC
Is 0 1 PWL 2,0 2.01,4 5,4 5.01,0
R10 1 0 5
R12 1 2 5
L20 2 0 20 IC=2.5
.tran 15 15 UIC
.probe
.end

I do not know if I have misunderstood the concept of the UIC command as
the book does not explain the command or the program in detail.I even
tried substituting the "SKIPBP" command instead of "UIC" and still got
the same result.I would be grateful if you could help me out.

Thank you,
Anand

[snip]

L20 has an "IC", irrespective of your UIC command.

Also, lose the commas as delimiters, they can confuse some netlisters.

...Jim Thompson

Seems strange.... The implication is that UIC (Use Initial Conditions)
should be substituted with IIC (Ignore Initial Conditions).....

DNA

There IS some discrepancy in the notation...

IC conditions on components seem always to be used.

...Jim Thompson

J
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