2007-07-19 - The feature rich PST Softstarters now offer two new important features: adjustable torque ramp control and a programmable analog communications output. The benefits of these new features include: linear starting and stopping of motors, elimination of water hammering, and mission critical data provided by analog loop communication. An HMI module allows upgrading an installed PST to the latest features. . . . Read More
Order Codes Unchanged
Since this is a new revision of the PST softstarter, the order codes remain the same. Identification of new features: A “T”symbol on the top left of the front label (see photo) as well as on the packing label indicates that the new functions are included.
Torque Control
With the new PST softstarter it is possible to select between the normal voltage ramp and the new torque ramp for both starting and stopping. When selecting torque ramp for start, the torque of the motor will follow a predefined optimal curve. This will ensure even smoother starting than before, resulting in a more linear acceleration of the motor speed.
When selecting torque ramp for stopping, the voltage will be adjusted so that the torque decreases from an operational level down to a value matching the set end voltage. This is especially useful when stopping pumps. The new torque ramp has improved control of the motor all the way down, close to zero speed, preventing water hammering from occurring even in the most difficult applications.
It is also possible to set a maximum torque allowed during starting by selecting the included torque limit function. This is an easy and convenient way of limiting the accelerating torque the machinery is exposed to, like couplings, gear boxes and similar. The torque ramp with torque limit reduces the wear on the equipment and drive components.
Analog Output
The new revision of the PST softstarter is also equipped with a programmable analog output signal. It can be set to 0 – 10V, 0 – 20mA or 4 – 20mA and it can be programmed to show, motor current, the motor temperature, main voltage, or active power, etc. The signal can be used for a direct feeding of an analog meter or directly connected to a PLC. The terminals used for analog output are also used for PTC protection, so only one of these functions can be used at a time.
Upgrading Installed PST's
It is possible to upgrade an earlier version of the PST softstarter to the latest version, by purchasing a new HMI module including: LV-card, HV-card and a new front of the softstarter, including the “T”-symbol. The HMI module is available in the PST spare part list.
for More Information see Related Links on this page