Inversion loss

and three-phase monitor


with protective cover


The DSP-1L or DSP-1LM is used to protect your three-phase motors against loss, imbalance or inversion. It continuously monitors each phase of your power supply. In case of phase loss, imbalance or inversion, the DSP-1L cuts off the power to the control circuit and thus protects the motor concerned.

The DSP-1LM is used to transmit a signal to a PLC. As soon as the three-phase power supply returns to normal, the DSP-1L enables the engine to restart normally and safely. However, the DSP-1LM’s Optomosfet contact will trip again.

Would you dare to connect your electrical equipment to a power supply not protected by fuses or circuit breakers? So now that
you know about the DSP-1L and DSP-1LM detectors, you know how to protect the production of your business against phase failures.

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DSP-1L by Controlab INC

Technical sheet of Phase Imbalance Detector (DSP-1L)

The contact of the DSP or DSP-1L-1LM is normally open. Once the phases are connected and no faults are detected, it closes after 2 or 3 seconds. It will open again as soon as a failure is detected. The detector’s epoxy coating provides very good protection against moisture, corrosion, dust and vibrations. No adjustment is required because our electronic circuit calibrated between 8% and 9% imbalance is completely sealed. The DSP-1L or DSP-1LM samples the voltage and not the current. It can therefore be installed on a 1 or 2,000 HP engine.

Also, our DSP-1L or DSP-1LM, in addition to being resistant to normal voltage fluctuations, is also equipped with a visual alarm indicator (LED).

For specific situations, a remote indicator light (GB-Kit Option) can be installed on the front of the control panel. The GB-Kit lights up regardless of the phase that is missing because it is not powered by the control transformer.

▶Human protection cover
▶Two (2) years warranty
▶CSA and UL approved
▶Fully cast in epoxy
▶Requires no secondary power source
▶Self-checking electronic circuit
▶High-quality design
▶Small design
▶Easy to install
▶No adjustment needed
Works under three-phase voltage
Available operating voltages: 600V, 480V, 240V, 208V
Operating frequencies: 50 Hz or 60 Hz
Current consumption: 6 mA
Response time: 2 to 3 seconds
Calibration: 8% to 9% imbalance
Option GB-Kit: NEMA-4X Remote Light

1- Can you connect a DSP-1L or DSP-1LM to single-phase or two-phase voltage?
No, because the DSP-1L or DSP-1LM works only with three-phase voltage.

2- To which three-phase voltages can a DSP-1L or DSP-1LM be connected?
All three-phase voltages between 208 volts and 600 volts (do not forget to specify the desired voltage when ordering).

3- Can a DSP-1L or DSP-1LM still be connected to a voltage of 1200 volts or more?
Yes, with the use of a PT (Potential Transformer) because what is occurring on the primary side of the transformer is the same as the secondary side. So if there is a loss, an inversion, or a phase imbalance at the transformer input, it will be automatically analyzed by the DSP-1L or DSP-1LM at the output of these transformers.

4- What are the switch-on and switch-off times of the DSP-1L or DSP-1LM?
The delay is between 2 and 3 seconds, both for switching on and off.

5- The DSP-1L or DSP-1LM is adjusted to have an imbalance between 8 and 9% because, during a phase loss, there is a regeneration that reach up to 90% of the nominal voltage on the missing phase. This results in very rapid heating of the engine, which will eventually burn out.
Our detector is adjusted to an imbalance between 8 and 9% for maximum protection.

6- The DSP-1L or DSP-1LM works on voltage and not current, so it can be installed on engines with 1 hp or 2000 hp and more.

7- The GB-KIT or the LED light on the DSP-1L or DSP-1LM turns on to indicate a phase loss, phase inversion, phase imbalance or internal malfunction in the device.

8- The GB-Kit or the LED light on the DSP-1L or DSP-1LM turns on regardless of the missing phase because it is not powered by the control transformer, but by the internal power supply of the detector.

9- If GB-KIT oscillates, there may be two reasons.
a) An imbalance between phases that is close to the tripping threshold of the unit.
b) A change in the values of the internal components that affects the sensitivity calibration, making it increasingly sensitive (So instead of 8 to 9%, it will trend towards zero).

10- Even if the LED light or GB-KIT oscillates, the DSP-1L or DSP-1LM contact will not oscillate. When the oscillation reaches a certain speed, the contact will open to interrupt the starter circuit.

11- The DSP-1L triac contact has a capacity between 24 VAC / 240 VAC, with a 4.0 amp maximum.
The triac contact can only operate with an AC supply, and not DC.

12- The DSP-1LM OptoMosfet contact has a capacity of 30 VDC / 120 VAC, with 120 milliamps. The maximum contact resistance of the OptoMosfet is 35 ohms.

13- How can the DSP-1L triac contact be tested?
a) Never test the triac contact with an ohmmeter because it will always produce a resistance value, whether it is open or closed.
b) With the diode tester, the triac contact can be tested.
c) By placing a light in series with the triac contact.
d) Normally, if the LED light or GB-Kit on the DSP-1L or DSP-1LM is turned on, the contact is open and if the LED light is off, the contact is closed and functional.

Easy Installation

DSP-1L is delivered “ready-to-install”; all calibrations have been performed with precision during manufacture. The DSP-1L is also adjusted to avoid false alarms. No need for auxiliary power, no rails, no plug-in modules to install. Due to its small size, it can be installed inside most control boxes.

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Controlab products (phase imbalance detectors, voltage detectors, ground fault monitors) are sold through a network of distributors and OEMs covering all of North America. For questions or comments about Controlab products, please contact us.

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