How does load shedding and backup power affect my Staycold?

Staycold products, like most commercial refrigerators require stable access to 220V, 50Hz power supply in order to operate efficiently and  effectively. Due to the ongoing load shedding we are experiencing in South Africa, we compiled information to extract the most use from a Staycold product under no supply or poor supply conditions.

No Supply


Due to the nature of their design, the internal air temperature of a Staycold unit will increase above the normal operating temperature within ± 30 minutes of a power failure. To combat this, some customers may look to power the unit using a backup supply source. The specification of alternative supply system should be decided upon after consultation with a qualified supplier of such equipment but there are some key points that should be considered:

  • The system should supply the unit with a pure sine wave, 220V, 50hz voltage supply.
  • The power of such a system should be such that it can supply at least 2x the amp rating of the unit indicated on the rating label of the unit (found on the inside left wall of the unit).
  • In the case of generators, the supply should be stable (i.e. not drop under load) particularly at the time of the compressor start up. Some generators experience a drop in supply when they come under load, only for a second or two, but such a drop may trigger the voltage protection on the unit.

Poor Supply

For the purposes of this article, poor supply is defined as when a unit has an AC supply, but the supply is such that it is outside of the 220V, 50Hz requirement of the unit, be it from the utility supply or generator/ invertor.

There are a few solutions available to customers that either combat or protect against poor supply related issues:

  • Surge protection – a device that limits the damage to a unit’s electrical components from voltage surges (very high momentary surges of voltage). It is important to understand that even if an item has surge protection, it does not mean that it is 100% safe from all surges – some surges may still get through and damage components. For an interesting article on surge protection, please see here.
  • Voltage protection – a device that monitors the incoming voltage and if it is found to be outside of working parameters, limits the onward supply of this voltage to downstream components that could be damaged by poor supply. Voltage protection does not necessarily provide protection against surges.
  • Voltage stabilization – This is a device that can boost or reduce an out of spec voltage to safe levels through use of a transformer. It can also provide surge protection. However, surges may cause damage to the voltage stabilizer itself.

The table below shows the features that come as standard on Staycold products as well as items that can be fitted as optional extra’s.

The voltage protection in a Staycold unit is provided by means of our Danfoss Energy Management Device. This device continuously monitors the incoming voltage to the unit. If it senses that the voltage is outside of requirements, then it automatically restricts the supply to the compressor and flashes a uLo alarm on the display of the controller. Once the controller senses that the voltage has returned to safe operating requirements it will then automatically disengage the protection and will once again allow voltage to flow to the compressor.

Staycold can supply, as an optional extra, voltage stabilizers that are able to boost or reduce out of specified voltages in the range of 145V to 270V to allow the units to operate.

We do not offer a surge protection solution and recommend that customers seek expert help from an electrical engineer or electrician as to what type of surge protection their facility requires.

We hope this information helps you get the most use out of your Staycold products during load shedding or when the power supply is affected and you have backup power.