Over Voltage Under Voltage Over/Under Voltage Current Under Current
Over/Under Current Over Frequency Under Frequency Over/Under Frequency
Phase Sequence Phase Failure Paralleling

LIMIT RELAYS Limit relays consist of a transducer and DC limit relay in one case. A potentiometer allows the limit to be adjusted. Dual limit relays contain two comparators and potentiometers operating into a single electro- mechanical relay. This relay is energized only if the input is between the two set values. Limit relays accept an input (voltage, current, frequency, etc.) compare it with a built-in standard, and change the state of a relay depending on whether the signal is above or below the standard. When sensing indi- cates a parameter is outside ad-justable predetermined limits, the unit energizes or deenergizes one or more relays. Limit relays are available for all the same types of measurement as our transducers. The state of the relay can be used to generate an alarm or to take corrective action. Single (High or Low) and dual (High or Low) units are available. Limits are externally adjustable. Average, RMS, or Peak sensing is available. Arga has excelled in developing combination relays for industrial and military use (under/ over voltage, reverse power, parallel- ing with fault memory available). METER RELAYS These relays contain an extra pair of output terminals which run analog, digital or bar meters. They also contain lights to indicate status. Meter Relay Modules may be used with any 0-1 mA analog or 0-2 VDC digital meter. Two or more meters may be driven by one module (or multiple monitoring can be accomplished using two or more modules for a single meter). The meter relay modules come with internal or ex- ternal signal conditioning. Any input can be monitored. Arga Meter Relays offer higher reliability and durability than standard or photoelectric types because they have no delicate contacts, locking coils, or magnets, and require no external power supply. PUMP and MOTOR PROTECTIVE RELAYS Loss of prime in pumps can cause damage since the pumped liquid no longer functions to transfer heat or lubricate, the pump overheats, and bearings and seals are destroyed, resulting in costly repairs. When a pump loses prime, the power drawn by the motor also decreases. A protective device must detect this under power. Arga's Pump Motor and Process Protection Relay is designed on this basis to protect motor driven pumps against loss of prime and cavitation. The entire device mounts in the motor control box. No addi- tional plumbing or wiring to the pump itself is required. Current and power trip points are adjustable. The current transformer is supplied.