Low-Cost Solutions for Preventing Motor and Pump Damage from Frequent Switching

For certain applications, such as in motor-driven systems, frequent switching on or off can easily damage the system. To avoid this, we may not want an immediate response on the secondary side but prefer a delay or only want the response to occur for a specific duration. A cost-effective solution to address this issue is to use a time relay.
A time relay is a control relay with a built-in delay function. It controls the circuit by powering on or off after a set time. There are two main types of time relays: delay-on and delay-off relays. These relays can be either normally open or normally closed, and the delay time can range from milliseconds to several days. Time relays are widely used in industrial applications, HVAC systems, building automation, energy management, process control, and wastewater treatment to provide delayed switching services. They are critical in targeted logic applications such as motor startups, controlling electrical loads, or automating specific actions.
Example: Wastewater Treatment Plant
In a wastewater treatment plant, when the water tank reaches a constant water level, the water surface may not remain still. It could have some ripples or waves, causing the float switch to produce an uncertain state. This fluctuation might result in the motor or pump being started and then stopped shortly after, simply due to the float switch’s movement. Ideally, the system should only switch when the water level stabilizes to improve the system’s reliability.
To prevent motor or pump misfires, a time relay with function E (delayed start), such as the HK-E1ZMQ10 24-240V AC/DC, can be used to delay the switch contact reading until the next available measurement, preventing "ripple switching." This reduces unnecessary system startups, protecting the motor and minimizing fault triggers, ultimately lowering maintenance costs.
Solution: Hongke HK-E1ZMQ10 Multifunction Time Relay
The HK-E1ZMQ10 24-240V AC/DC is a multifunctional time relay that supports several functions: E (delayed start), R (delayed off), Wu (single pulse leading edge control), and Bp (flashing pulse with pause priority). The E-function (delayed start) means when the supply voltage U is applied, the preset time interval t starts (green LED U/t blinks). Once the interval t ends (green LED U/t lights steadily), the output relay R switches to the on position (yellow LED lights). This state remains until the power voltage is interrupted.
Setup Procedure:
1. On the HK-E1ZMQ10 panel, use the bottom rotary switch to select the desired function. Point the long slot to the chosen letter (e.g., E for delay-on).
2. Use the middle rotary switch on the panel to set the time range. This dial allows you to set the timing range. For example, if the timing is 30 minutes, select the next highest value. In this case, 1 hour.
3. The final step is fine-tuning the time relay's timing. This works like a percentage system. If the desired delay time is 30 minutes and you set the time range to 1 hour in step 2, you’ll need to set the dial to 0.5, so the final timing would be: 1 hour × 0.5 = 0.5 hours = 30 minutes.
HK-E1ZMQ10 Features and Specifications:
- Supports up to 7 time ranges, allowing adjustments from 1 second to 100 hours.
- Includes 4 timing functions in one unit.
- A wide control voltage range of 24-240V instead of a single voltage.
- Two LEDs for continuous status monitoring.
- Ultra-wide and shifted terminals for easy wiring.