Benezan ElectronicsBEAST Stepper motor power stage
Hard- and software developmentInstallation Guide
Nicolas Benezan, Stauffenbergstr. 26, 72108 RottenburgPage 3
Phone: +49 (0) 7457/946455 Beast1D-Installationwww.benezan-electronics.de.docx 22.09.2020
3 Installation
3.1 Assembly
The output stage is designed for mounting on a 35mm DIN rail ("top-hat rail"). Hook the power amplifier into the rail
with the terminal side facing up, then press the bottom side with the control connection firmly onto the rail until it
snaps into place. Alternatively, it can also be mounted from the rear side with M3 screws or spacer bolts on a
mounting plate. Since the output stage becomes more or less hot during operation depending on the motor current,
the following rules must be observed during installation:
Make sure that there is free air circulation. The distance to other devices, housing wall, cable ducts, etc. should
be at least 2 cm on all sides.
If possible, the heat sink should be mounted vertically with vertical fins.
For horizontal mounting and motor current >4A, for vertical mounting >6A or at an ambient temperature
>40°C, forced cooling (fan) is required.
With a motor current >8A forced cooling is always necessary.
3.2 Power supply connection
The supply voltage must be between 24 and 80V. A stabilized power supply is not necessarily necessary, an
unregulated power supply consisting of transformer, rectifier and filter capacitor is completely sufficient. Please
note, however, that the voltage range must be maintained even with mains and load fluctuations (usually ±10%).
The maximum current with which the power supply unit is loaded is approx. 2/3 of the motor current. However,
the permanent load is lower in most applications. For the operation of 3 motors with 4A each, for example, a power
supply unit with 3 x 4A x 2/3 = 8A peak current and about 5A continuous load capacity is sufficient. An electrolytic
capacitor with about 1000μF per A motor current is recommended to keep voltage fluctuations caused by mains hum
and short load changes small. A little more won't hurt either, but the capacitor should not be too big either, otherwise
the current peaks in the rectifier and transformer will be too big.
Connect the positive pole of the power supply to terminal 1 (labelled 24..80V DC) and the negative pole to
terminal 2 (labelled Power Ground). Caution, wrong polarity can damage the power amplifier, especially if the
power supply does not have a fast fuse or current limiter
If necessary, several BEAST power amplifiers can be operated in parallel on one power supply unit. Please note
please ensure that the negative connection (Power Ground) is connected to the heat sink and therefore automatically to
the housing (potential earth) is connected. The connecting cables between the power supply unit and the power
amplifiers should be laid in a star shape and as short as possible, i.e. each power amplifier should have its own direct
connection to the power supply unit.
3.3 Motor connection
The output stage is suitable for the operation of two-phase motors. These usually have four or eight connections. For
motors with eight connections, two windings can be connected in parallel or in series. The following formula can be
helpful as a decision aid - serial or parallel: The supply voltage should be in the range of 10 to 25 times the rated
motor voltage. If the nominal voltage is not given, it can be calculated by multiplying the winding resistance by the
nominal current. Example:
Motor data: 8 connections, 0.8Ωper winding, rated current 3A per winding, 6A parallel
parallel connection 2x0.8Ωgives 0.4Ω* 6A = 2.4V Series connection: 2x0.8Ωgives 1.6Ω
* 3A = 4.8V
Line voltage 48V = 20 x 2.4V = 10 x 4.8V
In this case both types of connection would be possible. However, parallel connection allows higher speeds, and is
therefore usually preferred.
Motors with 6 terminals can also be used, but this is not recommended as these are mostly older models designed
for unipolar operation with obsolete power amplifiers. Old motors, which can usually be recognized by their round,
cylindrical housing, are not designed for microstep operation and exhibit increased vibration and reduced torque.
Connect one winding of the motor to terminals 3 and 4 (A-B), the second winding to terminals 5 and 6 (C-D). The
polarity and sequence is irrelevant for the function, but determines the direction of rotation of the motor. If the motor
turns in the wrong direction, this can be corrected by reversing the polarity of one (not both) of the windings.
Caution, never disconnect the terminal connection to the motor or power supply unit when the power supply unit
