Lovato PMA50A240 pump protection relay for single-phase and three-phase systems, providing maximum AC current, minimum power factor, phase loss and incorrect phase sequence monitoring.
£297.57
The Lovato PMA50A240 is a multifunction pump protection and current monitoring relay designed to protect single-phase and three-phase pump motors against abnormal operating conditions. As part of the dependable Lovato Electric PMA50 monitoring relay series, it combines maximum AC current monitoring with minimum power factor supervision to detect overloads, underload conditions and dry-running pumps.
The relay operates from a 220–240 V AC auxiliary supply and provides selectable 5 A or 16 A current measurement ranges. Motors drawing higher currents can be monitored through a suitable current transformer, giving panel builders and automation engineers flexibility across a wide range of pump sizes and installations.
In addition to overcurrent and dry-running protection, the PMA50A240 monitors phase loss and incorrect phase sequence in three-phase systems. Adjustable current, power factor and timing controls allow the relay to be configured around the characteristics of the connected pump, providing reliable protection without placing valuable equipment in the salt.
A pump motor can continue drawing current even when the pump is running dry, making conventional overcurrent protection alone insufficient. The Lovato PMA50A240 also monitors the motor power factor, allowing it to identify low-load conditions associated with dry running, loss of prime or insufficient fluid flow.
When an abnormal condition remains present beyond the selected delay, the relay de-energises its output contact. This can stop the pump, activate an alarm or transmit a fault signal to a PLC or building management system, helping prevent seal damage, overheating and premature pump failure.
| Voltage | 240 V |
|---|---|
| Phase | Single Phase |
| Manufacturer | Lovato Electric |
| Series | PMA50 |
| Model | PMA50A240 |
| Product type | Pump protection relay |
| System type | Single-phase and three-phase |
| Measured current type | AC |
| Monitoring functions | Maximum current, minimum cosφ, phase loss and incorrect phase sequence |
| Auxiliary supply voltage | 220–240 V AC |
| Rated frequency | 50 / 60 Hz |
| Selectable current ranges | 5 A or 16 A |
| Maximum current threshold adjustment | 5–100% of selected range |
| Minimum power factor adjustment | 0.10–0.99 cosφ |
| Connection | Direct or via current transformer |
| Relay outputs | 1 changeover contact |
| Contact configuration | SPDT |
| Conventional thermal current | 8 A |
| Output operating mode | Normally energised, de-energises on trip |
| Status indication | 1 green LED and 2 red trip LEDs |
| Terminal type | Screw terminals |
| Mounting type | DIN rail |
| Modular width | 3 modules |
| Front protection rating | IP40 |
| Terminal protection rating | IP20 |
| Operating temperature | -20°C to +60°C |
| Dimensions (W × H × D) | Approx. 53.5 × 104.7 × 64.9 mm |
| Electrical life | 100,000 operations at rated load |
| Mechanical life | 30,000,000 operations |
| HS Code | 85364900 |
The PMA50A240 protects single-phase and three-phase pumps against overcurrent, dry running, phase loss and incorrect phase sequence.
It monitors the motor power factor and trips when the measured cosφ falls below the selected minimum threshold, indicating that the pump may be running without sufficient load or fluid.
The relay provides selectable 5 A and 16 A ranges. Higher motor currents can be monitored using a suitable current transformer.
The relay operates from a 220–240 V AC auxiliary supply at 50 or 60 Hz.
Yes. In three-phase applications, the PMA50A240 detects phase loss and incorrect phase sequence before these conditions can damage the motor or cause incorrect pump rotation.
The relay mounts on a standard DIN rail inside a pump control panel and uses screw terminals for the supply, measurement and relay output connections.
Lovato Electric monitoring relays are used by panel builders, pump system installers and automation engineers to protect motors, detect abnormal operating conditions and improve the reliability of pumping installations.
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2025 has been a big year for LED Controls, and our blog has expanded accordingly. We've covered a wide range of topics across industrial control and factory automation this year. From core technology explainers and new product releases to panel building best practice...