gefran TPD32-EV-...-2B, Instructions Manual

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—————— TPD32-EV ——————
484
Figure A1.6.3.1: Detail of circuit
5
6
7
5
6
7
8
K
P
T
3
1
T
H
-C
T
E
x
te
r
n
a
l
burden
R
X
C
T
0VI
RCT
J5
J4
Armature current
feedback
2
R
5
2
R
5
S
W
3
,
S
W
4
N8
1
4
1
3
X
R
to
R
-T
P
D
3
2
FIRXP-XX board
fr
o
m
C
T
s
J5A
J4A
If the secondary current of the CTs installed is < 1 A, the 2.5 Ohm or 5 Ohm burden resistors already provided
on the card can be used; for secondary currents of >1 A and < 5 A the burden resistor must be connected between
terminals RCT and 0VI, excluding the internal resistors. In table form:
CT secondary current
< 0.5A > 0.5A, < 1A > 1A, < 5A
Jumper J4 J4A (OFF) J4 (ON) irrelevant
Jumper J5 J5 (ON) J5 (ON) J5A (OFF)
Ext. resistor RCT Not connected Not connected
See example of calculation
R resulting load (Rb) 5 Ohm 2,5 Ohm
n
ote
: Sometimes, especially in revamping projects, current transducers with a 5 A secondary cur -
rent may already be installed on the power bridges. It is still possible to use just the internal
resistors: simply insert two more 5 A/1 A or 5 A/0.5 A current transducers, although this could
affect the ultimate accuracy of current measurement.
- At 100% of the drive’s rated current (IdN), the average reaction voltage, applied between pins XR-13/
XR-14 (0 V) is 0.612 V .
- Dip-switch S3-1 represents the most significant bit (MSB) and dip-switch S4-8 the least significant bit
(LSB). A closed switch (“ON”) means binary value 1, an open switch (“OFF”) means 0. In graph form
SW3-1 SW3-2 SW3-3 SW3-4 SW4-1 SW4-2 SW4-3 SW4-4 SW4-5 SW4-6 SW4-7 SW4-8
bit 11
MSB
bit 10 bit 9 bit 8 bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0
LSB
- The maximum gain of the amplifier is 51.2 (in actual fact –51.2) and the minimum gain is 0.0125005
with possible values of 212 – 1.
- The binary configuration 00....000 (all S3 and S4 switches open), is not allowed!
- The relation between amplifier gain (“Gain_required”) and binary number (“Binary_switch_setting”)
is given by:
1 51,2
Binary_switch_setting = --------------------- x 51,2 = ---------------------
Gain_required Gain_required
Clearly, only the whole number of the result of the above equation is converted into a binary number.
The variables used in the following examples of calculation are:
- Id
N
= drive armature rated current in A;
- CT = current transducer with a transformation ratio of: Iprim/Isec;
- Rb = burden resistor in Ohm;
- Vf@Id
N
= reaction voltage at armature rated current: 0.612 V;
- Vb@Id
N
= reaction voltage on the burden resistor at the rated armature current in V.