Danfoss VLT series, Руководство по обслуживанию

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VLT is a registered Danfoss trademark
DRIVE INPUTS AND OUTPUTS
The drive operates by receiving control input signals. The drive
can also output status data or control auxiliary devices. Control
input is connected to the drive in three possible ways. One
way for drive control is through the keypad on the front of the
drive when operating in local (hand) mode. These inputs include
start, stop, reset, and speed reference.
Another control source is through serial communication from
a serial bus. A serial communication protocol supplies
commands and references to the drive, can program the drive,
and reads status data from the drive. The serial bus connects
to the drive through the RS-485 serial port or through a
communication option card.
The third way is through signal wiring connected to the drive
control terminals (see Figure 1-1). The drive control terminals
are located below the drive keypad. Improperly connected
control wiring can be the cause of a motor not operating or
the drive not responding to a remote input.
Input Signals
The drive can receive two types of remote input signals: digital
or analog. Digital inputs are wired to terminals 16, 17, 18, 19,
20 (common), 27, 29, 32, and 33. Analog inputs are wired to
terminals 53, 54, and 55 (common), or terminal 60.
Analog signals can be either voltage (0 to +10 VDC) connected
to terminals 53 and 54, or current (0 to 20 mA or 4 to 20 mA)
connected to terminal 60. Analog signals can be varied like
dialing a rheostat up and down. The drive can be programmed
to increase or decrease output in relation to the amount of
current or voltage. For example, a sensor or external controller
may supply a variable current or voltage. The drive output, in
turn, regulates the speed of the motor connected to the drive
in response to the analog signal.
Digital signals are a simple binary 0 or 1 which, in effect, act as
a switch. Digital signals are controlled by a 0 to 24 VDC signal.
A voltage signal lower than 5 VDC is a logic 0. A voltage higher
than 10 VDC is a logic 1. Zero is open, one is close. Digital
inputs to the drive are switched commands such as start,
stop, reverse, coast, reset, and so on. (Do not confuse these
digital inputs with serial communication formats where digital
bytes are grouped into communication words and protocols.)
The RS-485 serial communication connector is wired to
terminals (+) 68 and (-) 69. Terminal 61 is common and may
be used for terminating shields only when the control cable is
run between VLT drives, not between drives and other devices.
See
Grounding Shielded Cables in this section for correct
methods for terminating shielded control cable.
Output Signals
The drive also produces output signals that are carried through
either the RS-485 serial bus or terminals 42 and 45. Output
terminals 42 and 45 operate in the same manner as the inputs.
These terminals can be programmed for either a variable analog
signal in mA or a digital signal (0 or 1) in 24 VDC. In addition,
the terminals can provide a pulse reference of 0 to 32,000
pulses. Output analog signals generally indicate the drive
frequency, current, torque and so on to an external controller
or system. Digital outputs can be control signals used to open
or close a damper, for example, or send a start or stop
command to auxiliary equipment.
Additional terminals are 01, 02, and 03, which are a Form C
relay output. Terminals 04 and 05 are a Form A low voltage
relay output.
Terminals 12 and 13 provide 24 VDC low voltage power, often
used to supply power to the digital input terminals (16-33).
Those terminals must be supplied with power from either
terminal 12 or 13, or from a customer supplied external 24
VDC power source. Improperly connected control wiring is a
common service issue for a motor not operating or the drive
not responding to a remote input.
Figure 1-1. Control Terminals