Aetechron 7548RLY User manual

7548RLY / 7796RLY
Operator’s Manual Supplement
For Variable Very-Low Impedance Loads in Controlled Current Mode
574.295.9495 | www.AETechron.com
2507 Warren Street, Elkhart, IN 46516

7548RLY / 7796RLY OPERATOR’S MANUAL SUPPLEMENT
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1Introduction
The 7548RLY / 7796RLY amplifiers are special models of the AE Techron 7548 or 7796 amplifier that
have been modified to make them suitable for driving a Protection Relay or other variable very-low
impedance loads in controlled-current mode.
1.1 Features
Factory preset for Controlled Current Operation
Multi-pole Compensation optimized for resistive loads below 2 ohms.
1.2 About AE Techron
AE Techron focuses on the development of power conversion and amplifier solutions for difficult
environments. In addition to a line of standard power supplies and power amplifier products, AE Techron
provides the design and manufacture of custom, high-quality, low-volume electronic products for
research, military and industrial applications.
2Factory Configuration (Default Settings)
Your 7548RLY/7796RLY amplifier differs from standard 7548 or 7796 amplifier in the following ways:
1. The 7548RLY/7796RLY ships with Controlled Current set as the default mode of operation.
Note that the amplifier operation mode can be changed to Controlled Voltage mode by adjusting
the setting for Jumper J4, located on the amplifier main board (see the “Advanced Configuration”
section of the 7548/7796 Operator’s Manual).
2. The 7548RLY/7796RLY ships with a multi-pole compensation enabled for the Controlled Current
Mode Compensation Setting. The compensation is optimized for resistive loads below 2 ohms
but is stable with higher impedances.
Note that the amplifier Compensation Setting can be changed to the standard 7548/7796
setting by adjusting the setting for Jumper J5, located on the amplifier main board board (see the
“Advanced Configuration” section of the 7548/7796 Operator’s Manual).
This Supplement only provides information
specific to the 7548RLY and 7796RLY models
and is intended to be used together with the AE
Techron 7548 / 7796 Operator’s Manual.Please
refer to the Operator’s Manual for general
information about safety, installation, operation
and trouble-shooting.
NOTE

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3Setup, Operation and Troubleshooting
Please refer to the AE Techron 7548/7796 Operator’s Manual for 7548RLY/7796RLY Setup
Instructions. Note that the 7548RLY/7796RLY comes with the Mode setting pre-configured at the
factory for Controlled Current Hook-up.
Please refer to the AE Techron 7548/7796 Operator’s Manual for standard 7548RLY/7796RLY
Operation and Troubleshooting instructions.
The 7458RLY/7796RLY is designed for pulsed
operation and should not be run at high power
levels for long periods of time (greater than 5
minutes). Damage to components in the output
of the amplifier can result from extended high-
power usage (1,000 watts or above).

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3.1 Main Board Functions and Jumper Settings (Rev 3, 7548RLY/7796RLY)
Please refer to the following for details of main board jumper functions and the factory default settings.
KEY
NAME
REF.
DES.
DESCRIPTION
FACTORY
DEFAULT SETTING
A
Voltage Monitor
TL3
Observe the output voltage of the amplifier by
connecting an oscilloscope and/or voltmeter
from TL3, AMP OUT, to TL8 or TL18, GND,. This
test point reads voltage directly. A 10 Ω resistor
isolates it.
N/A
B
Master/Follower
Jumpers
P1 and
P2
ASSUMES BOTH JUMPERS MOVED TOGETHER
When the
MODEL 7548RLY/7796RLY
is used as
a single amplifier or as a master in a multi-amp
system, input is through the unbalanced BNC
connector on the rear panel and the
Master/Follower jumpers P1 and P2 will be in the
Master (UP) position. If the amplifier is used as a
follower in a multi-amp system, input will be
through the interface connector J3, and the
Master/Follower Jumpers P1 and P2 should be in
the Follower (DOWN) position.
MASTER (UP)
C
CC/CV Jumper
J4
This jumper goes RIGHT for Controlled Voltage
(CV
) mode, and LEFT for Controlled Current
(CC)
mode. By placing the jumper on the right pair of
pins, the amplifier's output voltage will be
controlled by its input voltage signal. By placing
the jumper on the left pair of pins, the input
voltage signal controls the output current.
CC (LEFT)
D
Compensation
Jumper
J5
The MODEL 7548RLY/7796RLY is factory-
configured to be used in the CC mode as a
controlled current amplifier. In CC mode, the
current control loop is optimized with an RC
network. The main board has provision for two of
these networks. When J5 is in the DOWN position
(default), the network CC2 (R82, C25) is selected.
When J5 is in the UP position, the alternate
network CC1 (R63, C16) is selected.
NOTE: For
RLY loads, the CC2 network must be used.
CC2 (DOWN)
E
Gain Trim Control
R210
This is a multi-turn potentiometer that is used to
calibrate the gain of the amplifier Turn clockwise
to increase gain; turn counter-clockwise to lower
gain. R232 resistor sets the coarse gain and
R247 sets the range or sensitivity of R210.
N/A
F
Circuit Ground
GND,
TL18
This point is the signal ground to be used as a
reference point for all measurements in the
amplified signal path.
N/A
G
System Current
Monitor
Ifb, TL2
This is the total system current feedback point for
amplifiers used in a multi-amplifier configuration.
N/A
H
Current Monitor
I MON,
TL4
The current monitor is an active buffered output
observable with monitoring equipment. The scale
factor is 20 Amps per Volt. Use GND (TL8), signal
ground, with I MON (TL4) to monitor amplifier
output current.
N/A
I
-TEMP and +TEMP
TL1 and
–TEMP and +TEMP are monitor points for the
N/A

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KEY
NAME
REF.
DES.
DESCRIPTION
FACTORY
DEFAULT SETTING
TL10
temperature sensors in the output wells. –TEMP
is used for the negative and +TEMP is used for
the positive wells. The output voltage is
measured in Kelvin, with 10 millivolts per degree
K. To convert readings to Celsius, subtract 273.
J
ENABLE / STOP
J11
The MODEL 7548RLY/7796RLY is factory-
configured to automatically move into ENABLE
mode on Start Up. In ENABLE mode, the amplifier
will amplify an input signal. To place the amplifier
in STOP mode on Start Up, move the jumper to
the two RIGHT pins. When in STOP mode on Start
Up, the amplifier will be placed in Standby mode
until the front-panel ENABLE button is pressed or
a remote ENABLE signal is received on the I/O
Connector. To return the amplifier to ENABLE
mode on Start Up, move the jumper to the two
LEFT pins.
ENABLE (LEFT)
K
OT Latch
J12
The MODEL 7548RLY/7796RLY is factory-
configured with the OT Latch disabled. When a
jumper is in place across the two pins labeled
J12, any activation of the Over Temp circuit will
cause the amplifier to move to a Stand By
condition and to remain there until the amplifier
is reset by pressing the front-panel RESET button,
or until a remote RESET signal is presented on
the I/O Connector, to return the amplifier to a
Run/Ready (Operational) condition.
DISABLED (jumper
absent)
L
OVLD Latch
J13
The MODEL 7548RLY/7796RLY is factory-
configured with the OVLD Latch disabled. When a
jumper is in place across the two pins labeled
J13, any activation of the IOC (Input Output
Comparator), distortion alert circuit, (activation
occurs at 0.5% error), will cause the amplifier to
move to a Stand By condition. Once in Stand By,
the amplifier must be reset by pressing the front-
panel RESET button, or by presenting a remote
RESET signal on the I/O Connector, to move the
amplifier back to a Run/Ready (Operational)
condition.
DISABLED (jumper
absent)
M
FOLLOWER GAIN
TRIM
R105
In multiple follower amplifier systems, this single-
turn potentiometer can be used to make minor
gain adjustments (+/- 2%) to balance the gain
with the rest of the system. Turn clockwise to
increase gain; turn counter-clockwise to lower
gain.
N/A
N
+VCC and -VCC
TL9 and
TL11
The point that the + (TL9) and – (TL11) voltage
potential of the amplifier can be monitored.
N/A

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The following illustration, showing the main board with captioned call-outs, provides a visual location of
main board functions (see Figure 3.1).
4Accuracy
Amplitude vs. Frequency at 1V input, 20A output,
amplifier transconductance set to 20:
Transconductance
Load
Input Signal
1 kHz
100 Hz
2 ohms Sine 19.9 20
1 ohm Sine 20 20
½ ohm Sine 20 20
Short
(unimpeded wire)
Sine 20 20
Figure 3.1 Main Board Component Locations

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5Specifications
Please refer to the AE Techron 7548/7796 Operator’s Manual “Specifications” section for basic amplifier
performance, features and physical characteristics. The following specifications apply to a 7548RLY/7796RLY
amplifier using the default factory settings.
7548 Pulse/Burst Specifications:
Maximum Current:
70 Arms, 100 Apeak
Maximum Voltage:
195 Vpeak
Total Load
Duration
Waveform
Output Power
0.5 ohm
20 seconds
60 Hz Sine 57 Arms/80.6 Apeak
DC 25 Apeak
0.5 second
60 Hz Sine 66 Arms/93 Apeak
DC 70 Apeak
0.2 second
60 Hz Sine 66 Arms/93 Apeak
DC 70 Apeak

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7796 Pulse/Burst Specifications:
Maximum Current: 141 Arms, 200 Apeak
Maximum Voltage: 183 Vpeak
Total Load Duration Waveform Output Power
0.19 ohm
20 seconds
60 Hz Sine 125 Arms/176 Apeak
DC 60 Apeak
0.5 second
60 Hz Sine 141 Arms/200 Apeak
DC 188 Apeak
0.2 second
60 Hz Sine 141 Arms/200 Apeak
DC 188 Apeak
0.53 ohm
1 minute
60 Hz Sine 91A rms/128 Apeak
DC 100 Apeak
0.5 second
60 Hz Sine 137A rms/193 Apeak
DC 164 Apeak
0.2 second
60 Hz Sine 139 Arms/196 Apeak
DC 164 Apeak
1.07 ohm
1 minute
60 Hz Sine 75A rms/107 Apeak
DC 66 Apeak
0.5 second
60 Hz Sine 83A rms/118 Apeak
DC 108 Apeak
0.2 second
60 Hz Sine 85A rms/120 Apeak
DC 108 Apeak

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Maximum Output Current:
7548RLY: 100 amps peak
7796RLY: 200 amps peak
Maximum Output Voltage:
7548RLY: 195 volts peak
7796RLY: 183 volts peak
Maximum Output Power:
Dependent on load and frequency
Load Constraint for Maximum Output:
7548RLY: 0.5 ohms + 200 microhenries
7796RLY: 0.19 ohms + 200 microhenries
* All loads from 8-ohm to short are stable with 2 mH in series.
Output Offset Current:
Less than 10.0 milliamperes DC peak
Input:
Standard Transconductance:20 ±0.2% from short to 1-ohm loads
Common Mode Rejection Ratio: -58 dB minimum, 40-600Hz
Unit to Unit Phase Error:
Less than ±0.1 degrees at 60Hz
Residual Noise:
Less than 2.5 milliamperes peak (40Hz - 600Hz)
Out Accuracy:
Less than ±1%

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Figure 5.2 7548RLY Back Panel
Figure 5.3 7796RLY Back Panel