6 pros Dry Run Protection Relay to protect water pump, chemical pump burns because of dry run

  Dry Run Protection Relay will protects Load Motor, Water Pump, Chemical Pump or Submersible Pump do not operate without water because it will make water pump have damage from mechanic or turbine which need water in system all the time. Drive set inside will have heat inside then melted cause a lot of damage to pump set. Normally, it must have protection set such as Dry Run Protection Relay to check when pump will have dry run condition because pump is expensive cost.   Dry Run Protection Relay will check the changed PF (Power Factor) value or pump current in case there are water in system, PF (Power Factor) or current will be high and PF (Power Factor) or current will be low without water. Dry Run Protection Relay will check irregular condition then cut off the water pump immediately. It can connect in 2 ways by choosing as motor rated current in Direct type. It can use with water pump maximum 40 Amp. And another way is connecting with the external CT by setting ratio as CT value. It can connect with 3 phase and 1 phase system in one device. Function Start Delay Timer delay time for waiting water full of tube then check system later.  Function Off Delay Timer delay when device cut the pump operation off. Function Recovery Time delay time when pump start operation automatic suit with Submersible Pump because it will comeback to operate automatic when water has dry as setting time. The device display PF and current (Amp) on screen.

Dry Run Protection Relay model PM-007N brand Primus

Dimension Dry Run Protection Relay model PM-007N brand Primus


     From last time we present  “วิธีป้องกันปั๊มน้ำ, ปั๊มเคมี ไหม้หรือเสียหาย ด้วย Dry Run Protection?” as we inform Dry Run Protection Relay about Function  Relay Output that user can choose these 2 Function

How to set PF to be Under Protection (Un)

How to set PF to be Over Protection (Ov)

     If measured value lower than Setpoint value from setting PF = 0.8 (depend on Name Plate Motor each model) Relay Output will order Motor after stop operate after complete OFF Delay Time (DT) from setting and back to operate again after Recovery Time (RT) by Dry Run will commend water pump motor again automatic (Auto) by this function is suitable with artesian well when water dry it cut the system off and back to operate when it has water again.

     If measured value higher than Setpoint value from setting. Relay Output will command motor stop operation after complete OFF Delay Time (DT) from setting. This function use with application that need to protect gear which has high ratio, slow round when it supports load more usual it will make damage to gear ** suit to check Load Protection current **


     Mostly people will see Dry Run Protection Relay in the industrial use to protect chemical industry, artesian well, wastewater Treatment, condominium etc. We can give you some example of circuit that how to use Dry Run Protection Relay in 1 phase and 3 phase as follow:

Example of circuit that how to use Dry Run Protection Relay in 1 phase


Dry Run Protection Relay check irregular condition of current (Amp) for 1 phase system suit to use with Motor 1 phase suitable for 1 Phase.

Mostly, it is Capacitor Motor which affects PF (Cosθ) value from measuring is unsure because capacitor connects with circle.



Example Circuit of  Dry Run Protection Relay for checking PF (Power Factor) (Cosθ) in 3 phase system


Dry Run Protection Relay check irregular condition in PF (Cosθ) value of Dry Run. It has change follow load more than current such as water pump in case water run out or no water. The PF value will low and obviously change. It can protect damage to pump in time.

     so we inform you about the operation of Dry Run Protection Relay with the example how to connect  Dry Run Protection Relay from above. We know the benefit of   Dry Run Protection Relay to protect water pump, chemical pump burn because water run out or dry by 6 things as follow:  

     6 pros Dry Run Protection Relay to protect water pump, chemical pump burns because dry run

1..Decrease the damage of water pump but keep out from mechanic system such as user no need to cut tube to install (Flow Switch need to cut tube to install).

2.Can install Dry Run Protection Relay in control cabinet convince to use.

3.Can pull the wires though Dry Run Protection Relay to check current (A) or check PF value directly and receive current maximum 40A.

4.Can use with large motor 10000 A (connect with external CT (Current Transformer)).

5. Saving install space.

6. Affordable price.

  Example of Application

 PM-007N application to protect water pump from dry run in chemical industry.