| Three Phase Voltage Monitors |
| Provide protection against: |
| Undervoltage and Overvoltage - Can cause motor overheating - Startup difficulties - Long term insulation damage - Overvoltage can cause internal arching - Both shorten motor life |
| Unbalanced Voltages - Can cause motor overheating in both stator windings and rotor bars - Can result in winding insulation failure - Most difficult fault to detect - Shortens motor life |
| Phase Loss - Most destructive fault condition - Motors may stall and fail in seconds - Motors cannot start under load |
| Phase Reversal - 3 phase motors may run backwards - May damage rotational sensitive equipment |
| Power Outages (Short Cycling) - Can result in short cycling - Often accompanied by low voltages - Some voltage monitors are available with time delays to prevent rapid restarting |
| Protects even when regenerative voltages are present |
| The most important feature to look for in a voltage monitor is sensitivity to unbalanced voltages. Sensitivity to unbalanced voltages is essential for reliable phase loss protection. The results of a side-by-side test conducted by ETL Laboratories in 1989, indicates that unless a voltage monitor is capable of detecting moderately unbalanced voltages, it may not sense phase loss faults when regenerated voltages are present. Regenerated voltages occur whenever the supply voltage to one phase of a rotating motor is lost. When regenerated voltages are present, the voltages will appear to be only about 8 to 10% unbalanced. However, during phase loss, the current draw in the remaining phases increases to over 150% of normal full load current. This extra current creates the captive heat that causes the winding insulation to fail. Voltage averaging types of line monitor designs are not designed to detect unbalanced voltages. |
| SSAC voltage monitors are backed by a 10 year warranty. Works with any size three phase motor. Easy installation and connections; Long wires are acceptable. Works with Delta Wye systems; No connection to neutral is required. Can detect phase loss and phase reversal before the motor is started. Will not allow the motor to start if a fault is present. |
| Single Phase AC Current Sensors |
| Sense Overcurrent, Undercurrent or Window Current Toroidal through hole wiring - no external CT is necessary. Adjustable or factory fixed delays to prevent nuisance tripping. Will sense AC currents up to 50A. SPDT Relay or solid state output versions are available. Direct connection to a PLC's input module Complete isolation between sensed current & control circuit DIN 3 mountable (some models) SSAC current sensors and monitors are backed by a 10 year warranty. Easy installation and connections; Long wires are acceptable. |
Copyright 2001 SSAC Inc Revised 02/04/04
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