Installation manual

GEO Direct PWM Amplifiers – Preliminary Documentation
System Wiring 19
Noise Problems
When problems do occur often it points to electrical noise as the source of the problem. When this occurs,
turn to controlling high-frequency current paths. If following the grounding instructions does not work,
insert chokes in the motor phases. These chokes can be as simple as several wraps of the individual motor
leads through a ferrite ring core (such as Micrometals T400-26D). This adds high-frequency impedance to
the outgoing motor cable thereby making it harder for high-frequency noise to leave the control cabinet
area. Care should be taken to be certain that the core’s temperature is in a reasonable range after installing
such devices.
Operating Temperature
It is important that the ambient operating temperature of the Geo Drive be kept within specifications. The
Geo Drive is installed in an enclosure such as a NEMA cabinet. The internal temperature of the cabinet
must be kept under the Geo Drive Ambient Temperature specifications. It is sometimes desirable to
roughly calculate the heat generated by the devices in the cabinet to determine if some type of ventilation
or air conditioning is required. For these calculations the Geo Drive’s internal heat losses must be known.
Budget 100W per axis for 1.5 amp drives, 150W per axis for 3 amp drives, 200W per axis for 5 amp
drives, 375W per axis for 10 Amp drives, and 500W per axis for 15 Amp drives.
Single Phase Operation
Due to the nature of power transfer physics, it is not recommended that any system design attempt to
consume more than 2kW from any single-phase mains supply. Even this level requires careful
considerations. The simple bridge rectifier front end of the Geo Drive, as with all other drives of this type,
require high peak currents. Attempting to transfer power from a single-phase system getting one charging
pulse each 8.3 milliseconds causes excessively high peak currents that can be limited by power mains
impedances. The Geo Drive output voltage sags, the input rectifiers are stressed, and these current pulses
cause power quality problems in other equipment connected to the same line. While it is possible to
operate drives on single-phase power, the actual power delivered to the motor must be considered. Never
design expecting more than 1.5 HP total from any 115V single-phase system and never more than 2.5 HP
from any 230V single-phase system.
Wiring AC Input
The main bus voltage supply is brought to the GEO drive through connector J1. 1.5 amp continuous and 3
amp continuous GEO drives can be run off single-phase power. It is acceptable to bring the single-phase
power into any two of the three input pins on connector J1. If not using one of the terminals, place a wire
jumper from the third terminal to one of the other two.
Higher-power drive amplifiers require three-phase input power. It is extremely important to provide fuse
protection or over-load protection to the input power to the GEO drive amplifier. Typically, this is
provided with fuses designed to be slow acting, such as FRN-type fuses. Due to the various regulations of
local codes, NEC codes, UL and CE requirements, it is very important to reference these requirements
before making a determination of how the input power is wired.
Additionally, many systems require that the power be able to be turned on and off in the cabinet. It is
typical that the AC power is run through some kind of main control contact within the cabinet, through
the fuses, and then fed to a GEO drive. If multiple GEO drives are used, it is important that each drive has
its own separate fuse block.
Whether single- or three-phase, it is important that the AC input wires be twisted together to eliminate
noise radiation as much as possible. Additionally, some applications may have further agency noise
reduction requirements that require that these lines be fed from an input filtering network.